feat: add mobile sidebar

app/books/bbd/[chapter]/page.tsx

@@ -11,6 +11,7 @@ import { Card, CardContent } from "@/components/ui/card";
 import { buttonVariants } from "@/components/ui/button";
 import { ChevronLeft, ChevronRight } from "lucide-react";
 import { cn } from "@/lib/utils";
+import { MobileNav, type MobileNavGroup } from "@/components/mobile-nav";
 
 // ---------------------------------------------------------------------------
 // Page
@@ -64,7 +65,12 @@ export default async function BbdChapterPage({
         {/* Main content */}
         <main className="flex-1 min-w-0 px-6 py-8 space-y-8">
           {/* Top navigation */}
-          <BbdNav prev={prev} next={next} />
+          <BbdNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
 
           {/* Content */}
           <Card>
@@ -82,7 +88,12 @@ export default async function BbdChapterPage({
           </Card>
 
           {/* Bottom navigation */}
-          <BbdNav prev={prev} next={next} />
+          <BbdNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
         </main>
       </div>
     </div>
@@ -174,31 +185,68 @@ function SidebarLink({
 function BbdNav({
   prev,
   next,
+  sidebarItems,
+  currentSlug,
 }: {
   prev: BbdSidebarItem | null;
   next: BbdSidebarItem | null;
+  sidebarItems: BbdSidebarItem[];
+  currentSlug: string;
 }) {
+  const mobileNavGroups: MobileNavGroup[] = [];
+  const introItems = sidebarItems.filter((i) => i.type === "intro-segment");
+  if (introItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Front Matter",
+      items: introItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/bbd/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+  const chapterItems = sidebarItems.filter((i) => i.type === "chapter");
+  if (chapterItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Chapters",
+      items: chapterItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/bbd/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
   return (
     <div className="flex items-center justify-between gap-3">
-      {prev ? (
-        <Link
-          href={`/books/bbd/${prev.slug}`}
-          className={cn(
-            buttonVariants({ variant: "outline", size: "sm" }),
-            "gap-1.5",
-          )}
-        >
-          <ChevronLeft className="size-4" />
-          <span className="hidden sm:inline truncate max-w-[180px]">
-            {prev.type === "chapter" && prev.chapter != null
-              ? `Ch. ${prev.chapter}`
-              : prev.label}
-          </span>
-          <span className="sm:hidden">Previous</span>
-        </Link>
-      ) : (
-        <div />
-      )}
+      <div className="flex items-center gap-2">
+        <MobileNav
+          groups={mobileNavGroups}
+          currentSlug={currentSlug}
+          bookTitle="Beyond Birth and Death"
+        />
+        {prev ? (
+          <Link
+            href={`/books/bbd/${prev.slug}`}
+            className={cn(
+              buttonVariants({ variant: "outline", size: "sm" }),
+              "gap-1.5",
+            )}
+          >
+            <ChevronLeft className="size-4" />
+            <span className="hidden sm:inline truncate max-w-[180px]">
+              {prev.type === "chapter" && prev.chapter != null
+                ? `Ch. ${prev.chapter}`
+                : prev.label}
+            </span>
+            <span className="sm:hidden">Previous</span>
+          </Link>
+        ) : (
+          <div className="hidden lg:block" />
+        )}
+      </div>
 
       {next ? (
         <Link

app/books/bg/[chapter]/[verse]/page.tsx

@@ -3,6 +3,7 @@ import { PageHeader } from "@/components/page-header";
 import { notFound } from "next/navigation";
 import { getBookMeta, getSingleVerse, getChapterVerseIndex } from "@/lib/api";
 import { ChapterViewer } from "@/app/books/chapter-viewer";
+import type { MobileNavGroup } from "@/components/mobile-nav";
 
 type BgMeta = {
   book: string;
@@ -42,6 +43,19 @@ export default async function VersePage({
   );
   if (!verse) notFound();
 
+  // Build mobile nav groups — single flat list of chapters
+  const mobileNavGroups: MobileNavGroup[] = [
+    {
+      title: "Chapters",
+      items: bgMeta.chapters.map((ch) => ({
+        slug: `${ch.number}`,
+        label: `${ch.number}. ${ch.title}`,
+        href: `/books/bg/${ch.number}/1`,
+        type: "chapter",
+      })),
+    },
+  ];
+
   return (
     <div className="min-h-screen bg-background">
       <PageHeader sticky wide>
@@ -70,6 +84,8 @@ export default async function VersePage({
           chapter={parseInt(chapter)}
           basePath={`/books/bg/${chapter}`}
           showBengali={false}
+          mobileNavGroups={mobileNavGroups}
+          mobileNavBookTitle="Bhagavad-gītā As It Is"
         />
       </div>
     </div>

app/books/cc/[lila]/[chapter]/[verse]/page.tsx

@@ -3,6 +3,7 @@ import { PageHeader } from "@/components/page-header";
 import { notFound } from "next/navigation";
 import { getBookMeta, getSingleVerse, getChapterVerseIndex } from "@/lib/api";
 import { ChapterViewer } from "@/app/books/chapter-viewer";
+import type { MobileNavGroup } from "@/components/mobile-nav";
 
 type ChapterInfo = {
   number: number;
@@ -49,6 +50,23 @@ export default async function CcVersePage({
   );
   if (!verseData) notFound();
 
+  // Build mobile nav groups from verse index
+  const mobileNavGroups: MobileNavGroup[] = [];
+  if (verseIndex.length > 0) {
+    mobileNavGroups.push({
+      title: "Verses",
+      items: verseIndex.map((v) => {
+        const label = v.verseEnd ? `${v.reference}` : v.reference;
+        return {
+          slug: String(v.verse),
+          label,
+          href: `/books/cc/${lila}/${chapter}/${v.verse}`,
+          type: "verse",
+        };
+      }),
+    });
+  }
+
   return (
     <div className="min-h-screen bg-background">
       <PageHeader sticky wide>
@@ -77,6 +95,8 @@ export default async function CcVersePage({
           chapter={parseInt(chapter)}
           showBengali={true}
           basePath={`/books/cc/${lila}/${chapter}`}
+          mobileNavGroups={mobileNavGroups}
+          mobileNavBookTitle={`${lilaInfo.name} — Chapter ${chapter}`}
         />
       </div>
     </div>

app/books/chapter-viewer.tsx

@@ -6,6 +6,7 @@ import { Card, CardHeader, CardContent } from "@/components/ui/card";
 import { Badge } from "@/components/ui/badge";
 import { Button } from "@/components/ui/button";
 import { ChevronLeft, ChevronRight, Loader2 } from "lucide-react";
+import { MobileNav, type MobileNavGroup } from "@/components/mobile-nav";
 
 // ---------------------------------------------------------------------------
 // Types
@@ -60,6 +61,10 @@ type ChapterViewerProps = {
   showBengali?: boolean;
   /** Base path for verse URLs, e.g. "/books/bg/1" — verse number is appended */
   basePath: string;
+  /** Mobile nav groups for the drawer */
+  mobileNavGroups?: MobileNavGroup[];
+  /** Book title for the mobile nav drawer header */
+  mobileNavBookTitle?: string;
 };
 
 // ---------------------------------------------------------------------------
@@ -72,12 +77,18 @@ function VerseNav({
   onPrev,
   onNext,
   verseIndex,
+  mobileNavGroups,
+  currentVerseSlug,
+  mobileNavBookTitle,
 }: {
   currentIdx: number;
   total: number;
   onPrev: () => void;
   onNext: () => void;
   verseIndex: VerseIndexEntry[];
+  mobileNavGroups?: MobileNavGroup[];
+  currentVerseSlug?: string;
+  mobileNavBookTitle?: string;
 }) {
   const hasPrev = currentIdx > 0;
   const hasNext = currentIdx < total - 1;
@@ -90,16 +101,25 @@ function VerseNav({
 
   return (
     <div className="flex items-center justify-between gap-3">
-      <Button
-        variant="outline"
-        size="sm"
-        disabled={!hasPrev}
-        onClick={onPrev}
-        className="gap-1.5"
-      >
-        <ChevronLeft className="size-4" />
-        <span className="hidden sm:inline">Previous</span>
-      </Button>
+      <div className="flex items-center gap-2">
+        {mobileNavGroups && mobileNavGroups.length > 0 && (
+          <MobileNav
+            groups={mobileNavGroups}
+            currentSlug={currentVerseSlug ?? String(current?.verse ?? "")}
+            bookTitle={mobileNavBookTitle}
+          />
+        )}
+        <Button
+          variant="outline"
+          size="sm"
+          disabled={!hasPrev}
+          onClick={onPrev}
+          className="gap-1.5"
+        >
+          <ChevronLeft className="size-4" />
+          <span className="hidden sm:inline">Previous</span>
+        </Button>
+      </div>
 
       <span className="text-sm text-muted-foreground">
         Verse {label} of {total}
@@ -220,6 +240,8 @@ export function ChapterViewer({
   chapter,
   showBengali = false,
   basePath,
+  mobileNavGroups,
+  mobileNavBookTitle,
 }: ChapterViewerProps) {
   const router = useRouter();
 
@@ -409,6 +431,9 @@ export function ChapterViewer({
           onPrev={goPrev}
           onNext={goNext}
           verseIndex={verseIndex}
+          mobileNavGroups={mobileNavGroups}
+          currentVerseSlug={String(currentVerseNum)}
+          mobileNavBookTitle={mobileNavBookTitle}
         />
 
         {/* Verse content */}
@@ -432,6 +457,9 @@ export function ChapterViewer({
           onPrev={goPrev}
           onNext={goNext}
           verseIndex={verseIndex}
+          mobileNavGroups={mobileNavGroups}
+          currentVerseSlug={String(currentVerseNum)}
+          mobileNavBookTitle={mobileNavBookTitle}
         />
       </main>
     </>

app/books/ds/[chapter]/page.tsx

@@ -11,6 +11,7 @@ import { Card, CardContent } from "@/components/ui/card";
 import { buttonVariants } from "@/components/ui/button";
 import { ChevronLeft, ChevronRight } from "lucide-react";
 import { cn } from "@/lib/utils";
+import { MobileNav, type MobileNavGroup } from "@/components/mobile-nav";
 
 // ---------------------------------------------------------------------------
 // Page
@@ -70,7 +71,12 @@ export default async function DsChapterPage({
         {/* Main content */}
         <main className="flex-1 min-w-0 px-6 py-8 space-y-8">
           {/* Top navigation */}
-          <DsNav prev={prev} next={next} />
+          <DsNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
 
           {/* Content */}
           <Card>
@@ -88,7 +94,12 @@ export default async function DsChapterPage({
           </Card>
 
           {/* Bottom navigation */}
-          <DsNav prev={prev} next={next} />
+          <DsNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
         </main>
       </div>
     </div>
@@ -204,29 +215,72 @@ function SidebarLink({
 function DsNav({
   prev,
   next,
+  sidebarItems,
+  currentSlug,
 }: {
   prev: DsSidebarItem | null;
   next: DsSidebarItem | null;
+  sidebarItems: DsSidebarItem[];
+  currentSlug: string;
 }) {
+  const mobileNavGroups: MobileNavGroup[] = [];
+
+  const introItems = sidebarItems.filter((i) => i.type === "intro-segment");
+  if (introItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Front Matter",
+      items: introItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/ds/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
+  const chapterItems = sidebarItems.filter(
+    (i) => i.type === "parent" || i.type === "sub-chapter",
+  );
+  if (chapterItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Chapters",
+      items: chapterItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/ds/${i.slug}`,
+        type: i.type,
+        parentChapter: i.parentChapter,
+        isParent: i.type === "parent",
+      })),
+    });
+  }
+
   return (
     <div className="flex items-center justify-between gap-3">
-      {prev ? (
-        <Link
-          href={`/books/ds/${prev.slug}`}
-          className={cn(
-            buttonVariants({ variant: "outline", size: "sm" }),
-            "gap-1.5",
-          )}
-        >
-          <ChevronLeft className="size-4" />
-          <span className="hidden sm:inline truncate max-w-[180px]">
-            {prev.label}
-          </span>
-          <span className="sm:hidden">Previous</span>
-        </Link>
-      ) : (
-        <div />
-      )}
+      <div className="flex items-center gap-2">
+        <MobileNav
+          groups={mobileNavGroups}
+          currentSlug={currentSlug}
+          bookTitle="Dialectic Spiritualism"
+        />
+        {prev ? (
+          <Link
+            href={`/books/ds/${prev.slug}`}
+            className={cn(
+              buttonVariants({ variant: "outline", size: "sm" }),
+              "gap-1.5",
+            )}
+          >
+            <ChevronLeft className="size-4" />
+            <span className="hidden sm:inline truncate max-w-[180px]">
+              {prev.label}
+            </span>
+            <span className="sm:hidden">Previous</span>
+          </Link>
+        ) : (
+          <div className="hidden lg:block" />
+        )}
+      </div>
 
       {next ? (
         <Link

app/books/ej/[chapter]/page.tsx

@@ -11,6 +11,7 @@ import { Card, CardContent } from "@/components/ui/card";
 import { buttonVariants } from "@/components/ui/button";
 import { ChevronLeft, ChevronRight } from "lucide-react";
 import { cn } from "@/lib/utils";
+import { MobileNav, type MobileNavGroup } from "@/components/mobile-nav";
 
 // ---------------------------------------------------------------------------
 // Page
@@ -64,7 +65,12 @@ export default async function EjChapterPage({
         {/* Main content */}
         <main className="flex-1 min-w-0 px-6 py-8 space-y-8">
           {/* Top navigation */}
-          <EjNav prev={prev} next={next} />
+          <EjNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
 
           {/* Content */}
           <Card>
@@ -82,7 +88,12 @@ export default async function EjChapterPage({
           </Card>
 
           {/* Bottom navigation */}
-          <EjNav prev={prev} next={next} />
+          <EjNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
         </main>
       </div>
     </div>
@@ -174,31 +185,70 @@ function SidebarLink({
 function EjNav({
   prev,
   next,
+  sidebarItems,
+  currentSlug,
 }: {
   prev: EjSidebarItem | null;
   next: EjSidebarItem | null;
+  sidebarItems: EjSidebarItem[];
+  currentSlug: string;
 }) {
+  const mobileNavGroups: MobileNavGroup[] = [];
+
+  const introItems = sidebarItems.filter((i) => i.type === "intro-segment");
+  if (introItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Front Matter",
+      items: introItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/ej/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
+  const chapterItems = sidebarItems.filter((i) => i.type === "chapter");
+  if (chapterItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Chapters",
+      items: chapterItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/ej/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
   return (
     <div className="flex items-center justify-between gap-3">
-      {prev ? (
-        <Link
-          href={`/books/ej/${prev.slug}`}
-          className={cn(
-            buttonVariants({ variant: "outline", size: "sm" }),
-            "gap-1.5",
-          )}
-        >
-          <ChevronLeft className="size-4" />
-          <span className="hidden sm:inline truncate max-w-[180px]">
-            {prev.type === "chapter" && prev.chapter != null
-              ? `Ch. ${prev.chapter}`
-              : prev.label}
-          </span>
-          <span className="sm:hidden">Previous</span>
-        </Link>
-      ) : (
-        <div />
-      )}
+      <div className="flex items-center gap-2">
+        <MobileNav
+          groups={mobileNavGroups}
+          currentSlug={currentSlug}
+          bookTitle="Easy Journey to Other Planets"
+        />
+        {prev ? (
+          <Link
+            href={`/books/ej/${prev.slug}`}
+            className={cn(
+              buttonVariants({ variant: "outline", size: "sm" }),
+              "gap-1.5",
+            )}
+          >
+            <ChevronLeft className="size-4" />
+            <span className="hidden sm:inline truncate max-w-[180px]">
+              {prev.type === "chapter" && prev.chapter != null
+                ? `Ch. ${prev.chapter}`
+                : prev.label}
+            </span>
+            <span className="sm:hidden">Previous</span>
+          </Link>
+        ) : (
+          <div className="hidden lg:block" />
+        )}
+      </div>
 
       {next ? (
         <Link

app/books/ek/[chapter]/page.tsx

@@ -11,6 +11,7 @@ import { Card, CardContent } from "@/components/ui/card";
 import { buttonVariants } from "@/components/ui/button";
 import { ChevronLeft, ChevronRight } from "lucide-react";
 import { cn } from "@/lib/utils";
+import { MobileNav, type MobileNavGroup } from "@/components/mobile-nav";
 
 // ---------------------------------------------------------------------------
 // Page
@@ -64,7 +65,12 @@ export default async function EkChapterPage({
         {/* Main content */}
         <main className="flex-1 min-w-0 px-6 py-8 space-y-8">
           {/* Top navigation */}
-          <EkNav prev={prev} next={next} />
+          <EkNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
 
           {/* Content */}
           <Card>
@@ -82,7 +88,12 @@ export default async function EkChapterPage({
           </Card>
 
           {/* Bottom navigation */}
-          <EkNav prev={prev} next={next} />
+          <EkNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
         </main>
       </div>
     </div>
@@ -174,31 +185,70 @@ function SidebarLink({
 function EkNav({
   prev,
   next,
+  sidebarItems,
+  currentSlug,
 }: {
   prev: EkSidebarItem | null;
   next: EkSidebarItem | null;
+  sidebarItems: EkSidebarItem[];
+  currentSlug: string;
 }) {
+  const mobileNavGroups: MobileNavGroup[] = [];
+
+  const introItems = sidebarItems.filter((i) => i.type === "intro-segment");
+  if (introItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Front Matter",
+      items: introItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/ek/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
+  const chapterItems = sidebarItems.filter((i) => i.type === "chapter");
+  if (chapterItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Chapters",
+      items: chapterItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/ek/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
   return (
     <div className="flex items-center justify-between gap-3">
-      {prev ? (
-        <Link
-          href={`/books/ek/${prev.slug}`}
-          className={cn(
-            buttonVariants({ variant: "outline", size: "sm" }),
-            "gap-1.5",
-          )}
-        >
-          <ChevronLeft className="size-4" />
-          <span className="hidden sm:inline truncate max-w-[180px]">
-            {prev.type === "chapter" && prev.chapter != null
-              ? `Ch. ${prev.chapter}`
-              : prev.label}
-          </span>
-          <span className="sm:hidden">Previous</span>
-        </Link>
-      ) : (
-        <div />
-      )}
+      <div className="flex items-center gap-2">
+        <MobileNav
+          groups={mobileNavGroups}
+          currentSlug={currentSlug}
+          bookTitle="Elevation to Kṛṣṇa Consciousness"
+        />
+        {prev ? (
+          <Link
+            href={`/books/ek/${prev.slug}`}
+            className={cn(
+              buttonVariants({ variant: "outline", size: "sm" }),
+              "gap-1.5",
+            )}
+          >
+            <ChevronLeft className="size-4" />
+            <span className="hidden sm:inline truncate max-w-[180px]">
+              {prev.type === "chapter" && prev.chapter != null
+                ? `Ch. ${prev.chapter}`
+                : prev.label}
+            </span>
+            <span className="sm:hidden">Previous</span>
+          </Link>
+        ) : (
+          <div className="hidden lg:block" />
+        )}
+      </div>
 
       {next ? (
         <Link

app/books/hkh/[chapter]/page.tsx

@@ -11,6 +11,7 @@ import { Card, CardContent } from "@/components/ui/card";
 import { buttonVariants } from "@/components/ui/button";
 import { ChevronLeft, ChevronRight } from "lucide-react";
 import { cn } from "@/lib/utils";
+import { MobileNav, type MobileNavGroup } from "@/components/mobile-nav";
 
 // ---------------------------------------------------------------------------
 // Page
@@ -64,7 +65,12 @@ export default async function HkhChapterPage({
         {/* Main content */}
         <main className="flex-1 min-w-0 px-6 py-8 space-y-8">
           {/* Top navigation */}
-          <HkhNav prev={prev} next={next} />
+          <HkhNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
 
           {/* Content */}
           <Card>
@@ -82,7 +88,12 @@ export default async function HkhChapterPage({
           </Card>
 
           {/* Bottom navigation */}
-          <HkhNav prev={prev} next={next} />
+          <HkhNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
         </main>
       </div>
     </div>
@@ -174,31 +185,70 @@ function SidebarLink({
 function HkhNav({
   prev,
   next,
+  sidebarItems,
+  currentSlug,
 }: {
   prev: HkhSidebarItem | null;
   next: HkhSidebarItem | null;
+  sidebarItems: HkhSidebarItem[];
+  currentSlug: string;
 }) {
+  const mobileNavGroups: MobileNavGroup[] = [];
+
+  const introItems = sidebarItems.filter((i) => i.type === "intro-segment");
+  if (introItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Front Matter",
+      items: introItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/hkh/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
+  const chapterItems = sidebarItems.filter((i) => i.type === "chapter");
+  if (chapterItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Chapters",
+      items: chapterItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/hkh/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
   return (
     <div className="flex items-center justify-between gap-3">
-      {prev ? (
-        <Link
-          href={`/books/hkh/${prev.slug}`}
-          className={cn(
-            buttonVariants({ variant: "outline", size: "sm" }),
-            "gap-1.5",
-          )}
-        >
-          <ChevronLeft className="size-4" />
-          <span className="hidden sm:inline truncate max-w-[180px]">
-            {prev.type === "chapter" && prev.chapter != null
-              ? `Ch. ${prev.chapter}`
-              : prev.label}
-          </span>
-          <span className="sm:hidden">Previous</span>
-        </Link>
-      ) : (
-        <div />
-      )}
+      <div className="flex items-center gap-2">
+        <MobileNav
+          groups={mobileNavGroups}
+          currentSlug={currentSlug}
+          bookTitle="The Kṛṣṇa Consciousness Handbook"
+        />
+        {prev ? (
+          <Link
+            href={`/books/hkh/${prev.slug}`}
+            className={cn(
+              buttonVariants({ variant: "outline", size: "sm" }),
+              "gap-1.5",
+            )}
+          >
+            <ChevronLeft className="size-4" />
+            <span className="hidden sm:inline truncate max-w-[180px]">
+              {prev.type === "chapter" && prev.chapter != null
+                ? `Ch. ${prev.chapter}`
+                : prev.label}
+            </span>
+            <span className="sm:hidden">Previous</span>
+          </Link>
+        ) : (
+          <div className="hidden lg:block" />
+        )}
+      </div>
 
       {next ? (
         <Link

app/books/iso/[mantra]/page.tsx

@@ -12,6 +12,7 @@ import { Card, CardContent } from "@/components/ui/card";
 import { buttonVariants } from "@/components/ui/button";
 import { ChevronLeft, ChevronRight } from "lucide-react";
 import { cn } from "@/lib/utils";
+import { MobileNav, type MobileNavGroup } from "@/components/mobile-nav";
 
 // ---------------------------------------------------------------------------
 // Type guards
@@ -79,14 +80,24 @@ export default async function IsoMantraPage({
         {/* Main content */}
         <main className="flex-1 min-w-0 px-6 py-8 space-y-8">
           {/* Top navigation */}
-          <IsoNav prev={prev} next={next} />
+          <IsoNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
 
           {/* Content */}
           {verse && <VerseContent verse={verse} />}
           {intro && <IntroContent intro={intro} />}
 
           {/* Bottom navigation */}
-          <IsoNav prev={prev} next={next} />
+          <IsoNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
         </main>
       </div>
     </div>
@@ -295,31 +306,90 @@ function SidebarLink({
 function IsoNav({
   prev,
   next,
+  sidebarItems,
+  currentSlug,
 }: {
   prev: IsoSidebarItem | null;
   next: IsoSidebarItem | null;
+  sidebarItems: IsoSidebarItem[];
+  currentSlug: string;
 }) {
+  const mobileNavGroups: MobileNavGroup[] = [];
+
+  // Front matter (front-pages + introduction)
+  const frontMatterItems = sidebarItems.filter(
+    (i) => i.slug === "intro-front-pages" || i.slug === "intro-introduction",
+  );
+  if (frontMatterItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Front Matter",
+      items: frontMatterItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/iso/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
+  // Mantras (invocation + 1-18)
+  const mantraItems = sidebarItems.filter((i) => i.type === "verse");
+  if (mantraItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Mantras",
+      items: mantraItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/iso/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
+  // Back matter (about-the-author)
+  const backMatterItems = sidebarItems.filter(
+    (i) => i.slug === "intro-about-the-author",
+  );
+  if (backMatterItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Back Matter",
+      items: backMatterItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/iso/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
   return (
     <div className="flex items-center justify-between gap-3">
-      {prev ? (
-        <Link
-          href={`/books/iso/${prev.slug}`}
-          className={cn(
-            buttonVariants({ variant: "outline", size: "sm" }),
-            "gap-1.5",
-          )}
-        >
-          <ChevronLeft className="size-4" />
-          <span className="hidden sm:inline truncate max-w-[180px]">
-            {prev.type === "verse" && prev.mantra != null && prev.mantra > 0
-              ? `Mantra ${prev.mantra}`
-              : prev.label}
-          </span>
-          <span className="sm:hidden">Previous</span>
-        </Link>
-      ) : (
-        <div />
-      )}
+      <div className="flex items-center gap-2">
+        <MobileNav
+          groups={mobileNavGroups}
+          currentSlug={currentSlug}
+          bookTitle="Śrī Īśopaniṣad"
+        />
+        {prev ? (
+          <Link
+            href={`/books/iso/${prev.slug}`}
+            className={cn(
+              buttonVariants({ variant: "outline", size: "sm" }),
+              "gap-1.5",
+            )}
+          >
+            <ChevronLeft className="size-4" />
+            <span className="hidden sm:inline truncate max-w-[180px]">
+              {prev.type === "verse" && prev.mantra != null && prev.mantra > 0
+                ? `Mantra ${prev.mantra}`
+                : prev.label}
+            </span>
+            <span className="sm:hidden">Previous</span>
+          </Link>
+        ) : (
+          <div className="hidden lg:block" />
+        )}
+      </div>
 
       {next ? (
         <Link

app/books/kb/[volume]/[slug]/page.tsx

@@ -6,6 +6,7 @@ import { Card, CardContent } from "@/components/ui/card";
 import { buttonVariants } from "@/components/ui/button";
 import { ChevronLeft, ChevronRight } from "lucide-react";
 import { cn } from "@/lib/utils";
+import { MobileNav, type MobileNavGroup } from "@/components/mobile-nav";
 
 export default async function KbChapterPage({
   params,
@@ -60,7 +61,13 @@ export default async function KbChapterPage({
         {/* Main content */}
         <main className="flex-1 min-w-0 px-6 py-8 space-y-8">
           {/* Top navigation */}
-          <ChapterNav prev={prev} next={next} volume={vol} />
+          <ChapterNav
+            prev={prev}
+            next={next}
+            volume={vol}
+            chapters={allChapters}
+            currentSlug={slug}
+          />
 
           {/* Chapter content */}
           <Card>
@@ -78,7 +85,13 @@ export default async function KbChapterPage({
           </Card>
 
           {/* Bottom navigation */}
-          <ChapterNav prev={prev} next={next} volume={vol} />
+          <ChapterNav
+            prev={prev}
+            next={next}
+            volume={vol}
+            chapters={allChapters}
+            currentSlug={slug}
+          />
         </main>
       </div>
     </div>
@@ -154,32 +167,71 @@ function ChapterNav({
   prev,
   next,
   volume,
+  chapters,
+  currentSlug,
 }: {
   prev: NavChapter | null;
   next: NavChapter | null;
   volume: number;
+  chapters: SidebarChapter[];
+  currentSlug: string;
 }) {
+  const mobileNavGroups: MobileNavGroup[] = [];
+
+  const introItems = chapters.filter((i) => i.type !== "chapter");
+  if (introItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Front Matter",
+      items: introItems.map((i) => ({
+        slug: i.slug,
+        label: i.title,
+        href: `/books/kb/${volume}/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
+  const chapterItems = chapters.filter((i) => i.type === "chapter");
+  if (chapterItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Chapters",
+      items: chapterItems.map((i) => ({
+        slug: i.slug,
+        label: i.chapter != null ? `${i.chapter}. ${i.title}` : i.title,
+        href: `/books/kb/${volume}/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
   return (
     <div className="flex items-center justify-between gap-3">
-      {prev ? (
-        <Link
-          href={`/books/kb/${volume}/${prev.slug}`}
-          className={cn(
-            buttonVariants({ variant: "outline", size: "sm" }),
-            "gap-1.5",
-          )}
-        >
-          <ChevronLeft className="size-4" />
-          <span className="hidden sm:inline truncate max-w-[180px]">
-            {prev.type === "chapter" && prev.chapter != null
-              ? `Ch. ${prev.chapter}`
-              : prev.title}
-          </span>
-          <span className="sm:hidden">Previous</span>
-        </Link>
-      ) : (
-        <div />
-      )}
+      <div className="flex items-center gap-2">
+        <MobileNav
+          groups={mobileNavGroups}
+          currentSlug={currentSlug}
+          bookTitle={`Kṛṣṇa Book — Volume ${volume}`}
+        />
+        {prev ? (
+          <Link
+            href={`/books/kb/${volume}/${prev.slug}`}
+            className={cn(
+              buttonVariants({ variant: "outline", size: "sm" }),
+              "gap-1.5",
+            )}
+          >
+            <ChevronLeft className="size-4" />
+            <span className="hidden sm:inline truncate max-w-[180px]">
+              {prev.type === "chapter" && prev.chapter != null
+                ? `Ch. ${prev.chapter}`
+                : prev.title}
+            </span>
+            <span className="sm:hidden">Previous</span>
+          </Link>
+        ) : (
+          <div className="hidden lg:block" />
+        )}
+      </div>
 
       {next ? (
         <Link

app/books/mg/[chapter]/page.tsx

@@ -11,6 +11,7 @@ import { Card, CardContent } from "@/components/ui/card";
 import { buttonVariants } from "@/components/ui/button";
 import { ChevronLeft, ChevronRight } from "lucide-react";
 import { cn } from "@/lib/utils";
+import { MobileNav, type MobileNavGroup } from "@/components/mobile-nav";
 
 // ---------------------------------------------------------------------------
 // Page
@@ -64,7 +65,12 @@ export default async function MgChapterPage({
         {/* Main content */}
         <main className="flex-1 min-w-0 px-6 py-8 space-y-8">
           {/* Top navigation */}
-          <MgNav prev={prev} next={next} />
+          <MgNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
 
           {/* Content */}
           <Card>
@@ -82,7 +88,12 @@ export default async function MgChapterPage({
           </Card>
 
           {/* Bottom navigation */}
-          <MgNav prev={prev} next={next} />
+          <MgNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
         </main>
       </div>
     </div>
@@ -174,31 +185,70 @@ function SidebarLink({
 function MgNav({
   prev,
   next,
+  sidebarItems,
+  currentSlug,
 }: {
   prev: MgSidebarItem | null;
   next: MgSidebarItem | null;
+  sidebarItems: MgSidebarItem[];
+  currentSlug: string;
 }) {
+  const mobileNavGroups: MobileNavGroup[] = [];
+
+  const introItems = sidebarItems.filter((i) => i.type === "intro-segment");
+  if (introItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Front Matter",
+      items: introItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/mg/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
+  const chapterItems = sidebarItems.filter((i) => i.type === "chapter");
+  if (chapterItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Chapters",
+      items: chapterItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/mg/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
   return (
     <div className="flex items-center justify-between gap-3">
-      {prev ? (
-        <Link
-          href={`/books/mg/${prev.slug}`}
-          className={cn(
-            buttonVariants({ variant: "outline", size: "sm" }),
-            "gap-1.5",
-          )}
-        >
-          <ChevronLeft className="size-4" />
-          <span className="hidden sm:inline truncate max-w-[180px]">
-            {prev.type === "chapter" && prev.chapter != null
-              ? `Ch. ${prev.chapter}`
-              : prev.label}
-          </span>
-          <span className="sm:hidden">Previous</span>
-        </Link>
-      ) : (
-        <div />
-      )}
+      <div className="flex items-center gap-2">
+        <MobileNav
+          groups={mobileNavGroups}
+          currentSlug={currentSlug}
+          bookTitle="Kṛṣṇa Consciousness: The Matchless Gift"
+        />
+        {prev ? (
+          <Link
+            href={`/books/mg/${prev.slug}`}
+            className={cn(
+              buttonVariants({ variant: "outline", size: "sm" }),
+              "gap-1.5",
+            )}
+          >
+            <ChevronLeft className="size-4" />
+            <span className="hidden sm:inline truncate max-w-[180px]">
+              {prev.type === "chapter" && prev.chapter != null
+                ? `Ch. ${prev.chapter}`
+                : prev.label}
+            </span>
+            <span className="sm:hidden">Previous</span>
+          </Link>
+        ) : (
+          <div className="hidden lg:block" />
+        )}
+      </div>
 
       {next ? (
         <Link

app/books/nod/[chapter]/page.tsx

@@ -11,6 +11,7 @@ import { Card, CardContent } from "@/components/ui/card";
 import { buttonVariants } from "@/components/ui/button";
 import { ChevronLeft, ChevronRight } from "lucide-react";
 import { cn } from "@/lib/utils";
+import { MobileNav, type MobileNavGroup } from "@/components/mobile-nav";
 
 // ---------------------------------------------------------------------------
 // Page
@@ -64,7 +65,12 @@ export default async function NodChapterPage({
         {/* Main content */}
         <main className="flex-1 min-w-0 px-6 py-8 space-y-8">
           {/* Top navigation */}
-          <NodNav prev={prev} next={next} />
+          <NodNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
 
           {/* Content */}
           <Card>
@@ -82,7 +88,12 @@ export default async function NodChapterPage({
           </Card>
 
           {/* Bottom navigation */}
-          <NodNav prev={prev} next={next} />
+          <NodNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
         </main>
       </div>
     </div>
@@ -197,31 +208,79 @@ function SidebarLink({
 function NodNav({
   prev,
   next,
+  sidebarItems,
+  currentSlug,
 }: {
   prev: NodSidebarItem | null;
   next: NodSidebarItem | null;
+  sidebarItems: NodSidebarItem[];
+  currentSlug: string;
 }) {
+  const mobileNavGroups: MobileNavGroup[] = [];
+
+  const introItems = sidebarItems.filter((i) => i.type === "intro-segment");
+  if (introItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Front Matter",
+      items: introItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/nod/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
+  const chapterItems = sidebarItems.filter((i) => i.type === "chapter");
+  const conclusionItems = sidebarItems.filter((i) => i.type === "conclusion");
+  if (chapterItems.length > 0 || conclusionItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Chapters",
+      items: [
+        ...chapterItems.map((i) => ({
+          slug: i.slug,
+          label: i.label,
+          href: `/books/nod/${i.slug}`,
+          type: i.type,
+        })),
+        ...conclusionItems.map((i) => ({
+          slug: i.slug,
+          label: i.label,
+          href: `/books/nod/${i.slug}`,
+          type: i.type,
+        })),
+      ],
+    });
+  }
+
   return (
     <div className="flex items-center justify-between gap-3">
-      {prev ? (
-        <Link
-          href={`/books/nod/${prev.slug}`}
-          className={cn(
-            buttonVariants({ variant: "outline", size: "sm" }),
-            "gap-1.5",
-          )}
-        >
-          <ChevronLeft className="size-4" />
-          <span className="hidden sm:inline truncate max-w-[180px]">
-            {prev.type === "chapter" && prev.chapter != null
-              ? `Ch. ${prev.chapter}`
-              : prev.label}
-          </span>
-          <span className="sm:hidden">Previous</span>
-        </Link>
-      ) : (
-        <div />
-      )}
+      <div className="flex items-center gap-2">
+        <MobileNav
+          groups={mobileNavGroups}
+          currentSlug={currentSlug}
+          bookTitle="The Nectar of Devotion"
+        />
+        {prev ? (
+          <Link
+            href={`/books/nod/${prev.slug}`}
+            className={cn(
+              buttonVariants({ variant: "outline", size: "sm" }),
+              "gap-1.5",
+            )}
+          >
+            <ChevronLeft className="size-4" />
+            <span className="hidden sm:inline truncate max-w-[180px]">
+              {prev.type === "chapter" && prev.chapter != null
+                ? `Ch. ${prev.chapter}`
+                : prev.label}
+            </span>
+            <span className="sm:hidden">Previous</span>
+          </Link>
+        ) : (
+          <div className="hidden lg:block" />
+        )}
+      </div>
 
       {next ? (
         <Link

app/books/noi/[text]/page.tsx

@@ -12,6 +12,7 @@ import { Card, CardContent } from "@/components/ui/card";
 import { buttonVariants } from "@/components/ui/button";
 import { ChevronLeft, ChevronRight } from "lucide-react";
 import { cn } from "@/lib/utils";
+import { MobileNav, type MobileNavGroup } from "@/components/mobile-nav";
 
 // ---------------------------------------------------------------------------
 // Type guards
@@ -79,14 +80,24 @@ export default async function NoiTextPage({
         {/* Main content */}
         <main className="flex-1 min-w-0 px-6 py-8 space-y-8">
           {/* Top navigation */}
-          <NoiNav prev={prev} next={next} />
+          <NoiNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
 
           {/* Content */}
           {verse && <VerseContent verse={verse} />}
           {intro && <IntroContent intro={intro} />}
 
           {/* Bottom navigation */}
-          <NoiNav prev={prev} next={next} />
+          <NoiNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
         </main>
       </div>
     </div>
@@ -210,9 +221,7 @@ function NoiSidebar({
   // Texts = 1-11
   const textItems = items.filter((item) => item.type === "verse");
   // Appendixes comes last
-  const appendixesItem = items.find(
-    (item) => item.slug === "intro-appendixes",
-  );
+  const appendixesItem = items.find((item) => item.slug === "intro-appendixes");
 
   return (
     <aside className="hidden lg:block w-56 shrink-0 sticky top-[89px] self-start max-h-[calc(100vh-89px)] overflow-y-auto py-8 pr-4">
@@ -295,31 +304,90 @@ function SidebarLink({
 function NoiNav({
   prev,
   next,
+  sidebarItems,
+  currentSlug,
 }: {
   prev: NoiSidebarItem | null;
   next: NoiSidebarItem | null;
+  sidebarItems: NoiSidebarItem[];
+  currentSlug: string;
 }) {
+  const mobileNavGroups: MobileNavGroup[] = [];
+
+  // Front matter (front-pages + preface)
+  const frontMatterItems = sidebarItems.filter(
+    (i) => i.slug === "intro-front-pages" || i.slug === "intro-preface",
+  );
+  if (frontMatterItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Front Matter",
+      items: frontMatterItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/noi/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
+  // Texts (1-11)
+  const textItems = sidebarItems.filter((i) => i.type === "verse");
+  if (textItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Texts",
+      items: textItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/noi/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
+  // Back matter (appendixes)
+  const backMatterItems = sidebarItems.filter(
+    (i) => i.slug === "intro-appendixes",
+  );
+  if (backMatterItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Back Matter",
+      items: backMatterItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/noi/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
   return (
     <div className="flex items-center justify-between gap-3">
-      {prev ? (
-        <Link
-          href={`/books/noi/${prev.slug}`}
-          className={cn(
-            buttonVariants({ variant: "outline", size: "sm" }),
-            "gap-1.5",
-          )}
-        >
-          <ChevronLeft className="size-4" />
-          <span className="hidden sm:inline truncate max-w-[180px]">
-            {prev.type === "verse" && prev.text != null
-              ? `Text ${prev.text}`
-              : prev.label}
-          </span>
-          <span className="sm:hidden">Previous</span>
-        </Link>
-      ) : (
-        <div />
-      )}
+      <div className="flex items-center gap-2">
+        <MobileNav
+          groups={mobileNavGroups}
+          currentSlug={currentSlug}
+          bookTitle="The Nectar of Instruction"
+        />
+        {prev ? (
+          <Link
+            href={`/books/noi/${prev.slug}`}
+            className={cn(
+              buttonVariants({ variant: "outline", size: "sm" }),
+              "gap-1.5",
+            )}
+          >
+            <ChevronLeft className="size-4" />
+            <span className="hidden sm:inline truncate max-w-[180px]">
+              {prev.type === "verse" && prev.text != null
+                ? `Text ${prev.text}`
+                : prev.label}
+            </span>
+            <span className="sm:hidden">Previous</span>
+          </Link>
+        ) : (
+          <div className="hidden lg:block" />
+        )}
+      </div>
 
       {next ? (
         <Link

app/books/ochkm/[chapter]/page.tsx

@@ -11,6 +11,7 @@ import { Card, CardContent } from "@/components/ui/card";
 import { buttonVariants } from "@/components/ui/button";
 import { ChevronLeft, ChevronRight } from "lucide-react";
 import { cn } from "@/lib/utils";
+import { MobileNav, type MobileNavGroup } from "@/components/mobile-nav";
 
 // ---------------------------------------------------------------------------
 // Page
@@ -64,7 +65,12 @@ export default async function OchkmChapterPage({
         {/* Main content */}
         <main className="flex-1 min-w-0 px-6 py-8 space-y-8">
           {/* Top navigation */}
-          <OchkmNav prev={prev} next={next} />
+          <OchkmNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
 
           {/* Content */}
           <Card>
@@ -82,7 +88,12 @@ export default async function OchkmChapterPage({
           </Card>
 
           {/* Bottom navigation */}
-          <OchkmNav prev={prev} next={next} />
+          <OchkmNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
         </main>
       </div>
     </div>
@@ -174,31 +185,70 @@ function SidebarLink({
 function OchkmNav({
   prev,
   next,
+  sidebarItems,
+  currentSlug,
 }: {
   prev: OchkmSidebarItem | null;
   next: OchkmSidebarItem | null;
+  sidebarItems: OchkmSidebarItem[];
+  currentSlug: string;
 }) {
+  const mobileNavGroups: MobileNavGroup[] = [];
+
+  const introItems = sidebarItems.filter((i) => i.type === "intro-segment");
+  if (introItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Front Matter",
+      items: introItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/ochkm/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
+  const chapterItems = sidebarItems.filter((i) => i.type === "chapter");
+  if (chapterItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Chapters",
+      items: chapterItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/ochkm/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
   return (
     <div className="flex items-center justify-between gap-3">
-      {prev ? (
-        <Link
-          href={`/books/ochkm/${prev.slug}`}
-          className={cn(
-            buttonVariants({ variant: "outline", size: "sm" }),
-            "gap-1.5",
-          )}
-        >
-          <ChevronLeft className="size-4" />
-          <span className="hidden sm:inline truncate max-w-[180px]">
-            {prev.type === "chapter" && prev.chapter != null
-              ? `Ch. ${prev.chapter}`
-              : prev.label}
-          </span>
-          <span className="sm:hidden">Previous</span>
-        </Link>
-      ) : (
-        <div />
-      )}
+      <div className="flex items-center gap-2">
+        <MobileNav
+          groups={mobileNavGroups}
+          currentSlug={currentSlug}
+          bookTitle="On Chanting the Hare Kṛṣṇa Mantra"
+        />
+        {prev ? (
+          <Link
+            href={`/books/ochkm/${prev.slug}`}
+            className={cn(
+              buttonVariants({ variant: "outline", size: "sm" }),
+              "gap-1.5",
+            )}
+          >
+            <ChevronLeft className="size-4" />
+            <span className="hidden sm:inline truncate max-w-[180px]">
+              {prev.type === "chapter" && prev.chapter != null
+                ? `Ch. ${prev.chapter}`
+                : prev.label}
+            </span>
+            <span className="sm:hidden">Previous</span>
+          </Link>
+        ) : (
+          <div className="hidden lg:block" />
+        )}
+      </div>
 
       {next ? (
         <Link

app/books/owk/[chapter]/page.tsx

@@ -11,6 +11,7 @@ import { Card, CardContent } from "@/components/ui/card";
 import { buttonVariants } from "@/components/ui/button";
 import { ChevronLeft, ChevronRight } from "lucide-react";
 import { cn } from "@/lib/utils";
+import { MobileNav, type MobileNavGroup } from "@/components/mobile-nav";
 
 // ---------------------------------------------------------------------------
 // Page
@@ -64,7 +65,12 @@ export default async function OwkChapterPage({
         {/* Main content */}
         <main className="flex-1 min-w-0 px-6 py-8 space-y-8">
           {/* Top navigation */}
-          <OwkNav prev={prev} next={next} />
+          <OwkNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
 
           {/* Content */}
           <Card>
@@ -82,7 +88,12 @@ export default async function OwkChapterPage({
           </Card>
 
           {/* Bottom navigation */}
-          <OwkNav prev={prev} next={next} />
+          <OwkNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
         </main>
       </div>
     </div>
@@ -174,31 +185,70 @@ function SidebarLink({
 function OwkNav({
   prev,
   next,
+  sidebarItems,
+  currentSlug,
 }: {
   prev: OwkSidebarItem | null;
   next: OwkSidebarItem | null;
+  sidebarItems: OwkSidebarItem[];
+  currentSlug: string;
 }) {
+  const mobileNavGroups: MobileNavGroup[] = [];
+
+  const introItems = sidebarItems.filter((i) => i.type === "intro-segment");
+  if (introItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Front Matter",
+      items: introItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/owk/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
+  const chapterItems = sidebarItems.filter((i) => i.type === "chapter");
+  if (chapterItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Chapters",
+      items: chapterItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/owk/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
   return (
     <div className="flex items-center justify-between gap-3">
-      {prev ? (
-        <Link
-          href={`/books/owk/${prev.slug}`}
-          className={cn(
-            buttonVariants({ variant: "outline", size: "sm" }),
-            "gap-1.5",
-          )}
-        >
-          <ChevronLeft className="size-4" />
-          <span className="hidden sm:inline truncate max-w-[180px]">
-            {prev.type === "chapter" && prev.chapter != null
-              ? `Ch. ${prev.chapter}`
-              : prev.label}
-          </span>
-          <span className="sm:hidden">Previous</span>
-        </Link>
-      ) : (
-        <div />
-      )}
+      <div className="flex items-center gap-2">
+        <MobileNav
+          groups={mobileNavGroups}
+          currentSlug={currentSlug}
+          bookTitle="On the Way to Kṛṣṇa"
+        />
+        {prev ? (
+          <Link
+            href={`/books/owk/${prev.slug}`}
+            className={cn(
+              buttonVariants({ variant: "outline", size: "sm" }),
+              "gap-1.5",
+            )}
+          >
+            <ChevronLeft className="size-4" />
+            <span className="hidden sm:inline truncate max-w-[180px]">
+              {prev.type === "chapter" && prev.chapter != null
+                ? `Ch. ${prev.chapter}`
+                : prev.label}
+            </span>
+            <span className="sm:hidden">Previous</span>
+          </Link>
+        ) : (
+          <div className="hidden lg:block" />
+        )}
+      </div>
 
       {next ? (
         <Link

app/books/poy/[chapter]/page.tsx

@@ -11,6 +11,7 @@ import { Card, CardContent } from "@/components/ui/card";
 import { buttonVariants } from "@/components/ui/button";
 import { ChevronLeft, ChevronRight } from "lucide-react";
 import { cn } from "@/lib/utils";
+import { MobileNav, type MobileNavGroup } from "@/components/mobile-nav";
 
 // ---------------------------------------------------------------------------
 // Page
@@ -64,7 +65,12 @@ export default async function PoyChapterPage({
         {/* Main content */}
         <main className="flex-1 min-w-0 px-6 py-8 space-y-8">
           {/* Top navigation */}
-          <PoyNav prev={prev} next={next} />
+          <PoyNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
 
           {/* Content */}
           <Card>
@@ -82,7 +88,12 @@ export default async function PoyChapterPage({
           </Card>
 
           {/* Bottom navigation */}
-          <PoyNav prev={prev} next={next} />
+          <PoyNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
         </main>
       </div>
     </div>
@@ -174,31 +185,70 @@ function SidebarLink({
 function PoyNav({
   prev,
   next,
+  sidebarItems,
+  currentSlug,
 }: {
   prev: PoySidebarItem | null;
   next: PoySidebarItem | null;
+  sidebarItems: PoySidebarItem[];
+  currentSlug: string;
 }) {
+  const mobileNavGroups: MobileNavGroup[] = [];
+
+  const introItems = sidebarItems.filter((i) => i.type === "intro-segment");
+  if (introItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Front Matter",
+      items: introItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/poy/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
+  const chapterItems = sidebarItems.filter((i) => i.type === "chapter");
+  if (chapterItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Chapters",
+      items: chapterItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/poy/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
   return (
     <div className="flex items-center justify-between gap-3">
-      {prev ? (
-        <Link
-          href={`/books/poy/${prev.slug}`}
-          className={cn(
-            buttonVariants({ variant: "outline", size: "sm" }),
-            "gap-1.5",
-          )}
-        >
-          <ChevronLeft className="size-4" />
-          <span className="hidden sm:inline truncate max-w-[180px]">
-            {prev.type === "chapter" && prev.chapter != null
-              ? `Ch. ${prev.chapter}`
-              : prev.label}
-          </span>
-          <span className="sm:hidden">Previous</span>
-        </Link>
-      ) : (
-        <div />
-      )}
+      <div className="flex items-center gap-2">
+        <MobileNav
+          groups={mobileNavGroups}
+          currentSlug={currentSlug}
+          bookTitle="The Perfection of Yoga"
+        />
+        {prev ? (
+          <Link
+            href={`/books/poy/${prev.slug}`}
+            className={cn(
+              buttonVariants({ variant: "outline", size: "sm" }),
+              "gap-1.5",
+            )}
+          >
+            <ChevronLeft className="size-4" />
+            <span className="hidden sm:inline truncate max-w-[180px]">
+              {prev.type === "chapter" && prev.chapter != null
+                ? `Ch. ${prev.chapter}`
+                : prev.label}
+            </span>
+            <span className="sm:hidden">Previous</span>
+          </Link>
+        ) : (
+          <div className="hidden lg:block" />
+        )}
+      </div>
 
       {next ? (
         <Link

app/books/pqpa/[chapter]/page.tsx

@@ -11,6 +11,7 @@ import { Card, CardContent } from "@/components/ui/card";
 import { buttonVariants } from "@/components/ui/button";
 import { ChevronLeft, ChevronRight } from "lucide-react";
 import { cn } from "@/lib/utils";
+import { MobileNav, type MobileNavGroup } from "@/components/mobile-nav";
 
 // ---------------------------------------------------------------------------
 // Page
@@ -64,7 +65,12 @@ export default async function PqpaChapterPage({
         {/* Main content */}
         <main className="flex-1 min-w-0 px-6 py-8 space-y-8">
           {/* Top navigation */}
-          <PqpaNav prev={prev} next={next} />
+          <PqpaNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
 
           {/* Content */}
           <Card>
@@ -82,7 +88,12 @@ export default async function PqpaChapterPage({
           </Card>
 
           {/* Bottom navigation */}
-          <PqpaNav prev={prev} next={next} />
+          <PqpaNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
         </main>
       </div>
     </div>
@@ -233,31 +244,108 @@ function SidebarLink({
 function PqpaNav({
   prev,
   next,
+  sidebarItems,
+  currentSlug,
 }: {
   prev: PqpaSidebarItem | null;
   next: PqpaSidebarItem | null;
+  sidebarItems: PqpaSidebarItem[];
+  currentSlug: string;
 }) {
+  const mobileNavGroups: MobileNavGroup[] = [];
+
+  const frontMatterItems: PqpaSidebarItem[] = [];
+  const chapterItems: PqpaSidebarItem[] = [];
+  const conclusionItems: PqpaSidebarItem[] = [];
+  const backMatterItems: PqpaSidebarItem[] = [];
+  let pastChapters = false;
+
+  for (const item of sidebarItems) {
+    if (item.type === "chapter") {
+      pastChapters = true;
+      chapterItems.push(item);
+    } else if (item.type === "conclusion") {
+      pastChapters = true;
+      conclusionItems.push(item);
+    } else if (!pastChapters) {
+      frontMatterItems.push(item);
+    } else {
+      backMatterItems.push(item);
+    }
+  }
+
+  if (frontMatterItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Front Matter",
+      items: frontMatterItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/pqpa/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
+  if (chapterItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Chapters",
+      items: [
+        ...chapterItems.map((i) => ({
+          slug: i.slug,
+          label: i.label,
+          href: `/books/pqpa/${i.slug}`,
+          type: i.type,
+        })),
+        ...conclusionItems.map((i) => ({
+          slug: i.slug,
+          label: i.label,
+          href: `/books/pqpa/${i.slug}`,
+          type: i.type,
+        })),
+      ],
+    });
+  }
+
+  if (backMatterItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Back Matter",
+      items: backMatterItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/pqpa/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
   return (
     <div className="flex items-center justify-between gap-3">
-      {prev ? (
-        <Link
-          href={`/books/pqpa/${prev.slug}`}
-          className={cn(
-            buttonVariants({ variant: "outline", size: "sm" }),
-            "gap-1.5",
-          )}
-        >
-          <ChevronLeft className="size-4" />
-          <span className="hidden sm:inline truncate max-w-[180px]">
-            {prev.type === "chapter" && prev.chapter != null
-              ? `Ch. ${prev.chapter}`
-              : prev.label}
-          </span>
-          <span className="sm:hidden">Previous</span>
-        </Link>
-      ) : (
-        <div />
-      )}
+      <div className="flex items-center gap-2">
+        <MobileNav
+          groups={mobileNavGroups}
+          currentSlug={currentSlug}
+          bookTitle="Perfect Questions Perfect Answers"
+        />
+        {prev ? (
+          <Link
+            href={`/books/pqpa/${prev.slug}`}
+            className={cn(
+              buttonVariants({ variant: "outline", size: "sm" }),
+              "gap-1.5",
+            )}
+          >
+            <ChevronLeft className="size-4" />
+            <span className="hidden sm:inline truncate max-w-[180px]">
+              {prev.type === "chapter" && prev.chapter != null
+                ? `Ch. ${prev.chapter}`
+                : prev.label}
+            </span>
+            <span className="sm:hidden">Previous</span>
+          </Link>
+        ) : (
+          <div className="hidden lg:block" />
+        )}
+      </div>
 
       {next ? (
         <Link

app/books/rv/[chapter]/page.tsx

@@ -11,6 +11,7 @@ import { Card, CardContent } from "@/components/ui/card";
 import { buttonVariants } from "@/components/ui/button";
 import { ChevronLeft, ChevronRight } from "lucide-react";
 import { cn } from "@/lib/utils";
+import { MobileNav, type MobileNavGroup } from "@/components/mobile-nav";
 
 // ---------------------------------------------------------------------------
 // Page
@@ -64,7 +65,12 @@ export default async function RvChapterPage({
         {/* Main content */}
         <main className="flex-1 min-w-0 px-6 py-8 space-y-8">
           {/* Top navigation */}
-          <RvNav prev={prev} next={next} />
+          <RvNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
 
           {/* Content */}
           <Card>
@@ -82,7 +88,12 @@ export default async function RvChapterPage({
           </Card>
 
           {/* Bottom navigation */}
-          <RvNav prev={prev} next={next} />
+          <RvNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
         </main>
       </div>
     </div>
@@ -174,31 +185,70 @@ function SidebarLink({
 function RvNav({
   prev,
   next,
+  sidebarItems,
+  currentSlug,
 }: {
   prev: RvSidebarItem | null;
   next: RvSidebarItem | null;
+  sidebarItems: RvSidebarItem[];
+  currentSlug: string;
 }) {
+  const mobileNavGroups: MobileNavGroup[] = [];
+
+  const introItems = sidebarItems.filter((i) => i.type === "intro-segment");
+  if (introItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Front Matter",
+      items: introItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/rv/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
+  const chapterItems = sidebarItems.filter((i) => i.type === "chapter");
+  if (chapterItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Chapters",
+      items: chapterItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/rv/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
   return (
     <div className="flex items-center justify-between gap-3">
-      {prev ? (
-        <Link
-          href={`/books/rv/${prev.slug}`}
-          className={cn(
-            buttonVariants({ variant: "outline", size: "sm" }),
-            "gap-1.5",
-          )}
-        >
-          <ChevronLeft className="size-4" />
-          <span className="hidden sm:inline truncate max-w-[180px]">
-            {prev.type === "chapter" && prev.chapter != null
-              ? `Ch. ${prev.chapter}`
-              : prev.label}
-          </span>
-          <span className="sm:hidden">Previous</span>
-        </Link>
-      ) : (
-        <div />
-      )}
+      <div className="flex items-center gap-2">
+        <MobileNav
+          groups={mobileNavGroups}
+          currentSlug={currentSlug}
+          bookTitle="Rāja-vidyā: The King of Knowledge"
+        />
+        {prev ? (
+          <Link
+            href={`/books/rv/${prev.slug}`}
+            className={cn(
+              buttonVariants({ variant: "outline", size: "sm" }),
+              "gap-1.5",
+            )}
+          >
+            <ChevronLeft className="size-4" />
+            <span className="hidden sm:inline truncate max-w-[180px]">
+              {prev.type === "chapter" && prev.chapter != null
+                ? `Ch. ${prev.chapter}`
+                : prev.label}
+            </span>
+            <span className="sm:hidden">Previous</span>
+          </Link>
+        ) : (
+          <div className="hidden lg:block" />
+        )}
+      </div>
 
       {next ? (
         <Link

app/books/sb/[canto]/[chapter]/[verse]/page.tsx

@@ -3,6 +3,7 @@ import { PageHeader } from "@/components/page-header";
 import { notFound } from "next/navigation";
 import { getBookMeta, getSingleVerse, getChapterVerseIndex } from "@/lib/api";
 import { ChapterViewer } from "@/app/books/chapter-viewer";
+import type { MobileNavGroup } from "@/components/mobile-nav";
 
 type ChapterInfo = {
   number: number;
@@ -48,6 +49,20 @@ export default async function SbVersePage({
   );
   if (!verseData) notFound();
 
+  const mobileNavGroups: MobileNavGroup[] = [
+    {
+      title: "Verses",
+      items: verseIndex.map((v) => ({
+        slug: String(v.verse),
+        label: v.verseEnd
+          ? `Texts ${v.verse}–${v.verseEnd}`
+          : `Text ${v.verse}`,
+        href: `/books/sb/${canto}/${chapter}/${v.verse}`,
+        type: "verse",
+      })),
+    },
+  ];
+
   return (
     <div className="min-h-screen bg-background">
       <PageHeader sticky wide>
@@ -76,6 +91,8 @@ export default async function SbVersePage({
           chapter={parseInt(chapter)}
           showBengali={false}
           basePath={`/books/sb/${canto}/${chapter}`}
+          mobileNavGroups={mobileNavGroups}
+          mobileNavBookTitle={`SB ${canto}.${chapter}`}
         />
       </div>
     </div>

app/books/sb1962/[chapter]/[verse]/page.tsx

@@ -3,6 +3,7 @@ import { PageHeader } from "@/components/page-header";
 import { notFound } from "next/navigation";
 import { getBookMeta, getSingleVerse, getChapterVerseIndex } from "@/lib/api";
 import { ChapterViewer } from "@/app/books/chapter-viewer";
+import type { MobileNavGroup } from "@/components/mobile-nav";
 
 type Sb1962Meta = {
   book: string;
@@ -46,6 +47,23 @@ export default async function VersePage({
   );
   if (!verse) notFound();
 
+  const mobileNavGroups: MobileNavGroup[] = [
+    {
+      title: "Verses",
+      items: verseIndex.map((v) => {
+        const label = v.verseEnd
+          ? `Verses ${v.verse}–${v.verseEnd}`
+          : `Verse ${v.verse}`;
+        return {
+          slug: String(v.verse),
+          label,
+          href: `/books/sb1962/${chapter}/${v.verse}`,
+          type: "verse",
+        };
+      }),
+    },
+  ];
+
   return (
     <div className="min-h-screen bg-background">
       <PageHeader sticky wide>
@@ -74,6 +92,8 @@ export default async function VersePage({
           chapter={parseInt(chapter)}
           basePath={`/books/sb1962/${chapter}`}
           showBengali={false}
+          mobileNavGroups={mobileNavGroups}
+          mobileNavBookTitle={`Śrīmad-Bhāgavatam (1962) — Ch. ${chapter}`}
         />
       </div>
     </div>

app/books/ssr/[chapter]/page.tsx

@@ -11,6 +11,7 @@ import { Card, CardContent } from "@/components/ui/card";
 import { buttonVariants } from "@/components/ui/button";
 import { ChevronLeft, ChevronRight } from "lucide-react";
 import { cn } from "@/lib/utils";
+import { MobileNav, type MobileNavGroup } from "@/components/mobile-nav";
 
 // ---------------------------------------------------------------------------
 // Page
@@ -70,7 +71,12 @@ export default async function SsrChapterPage({
         {/* Main content */}
         <main className="flex-1 min-w-0 px-6 py-8 space-y-8">
           {/* Top navigation */}
-          <SsrNav prev={prev} next={next} />
+          <SsrNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
 
           {/* Content */}
           <Card>
@@ -88,7 +94,12 @@ export default async function SsrChapterPage({
           </Card>
 
           {/* Bottom navigation */}
-          <SsrNav prev={prev} next={next} />
+          <SsrNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
         </main>
       </div>
     </div>
@@ -225,29 +236,89 @@ function SidebarLink({
 function SsrNav({
   prev,
   next,
+  sidebarItems,
+  currentSlug,
 }: {
   prev: SsrSidebarItem | null;
   next: SsrSidebarItem | null;
+  sidebarItems: SsrSidebarItem[];
+  currentSlug: string;
 }) {
+  const mobileNavGroups: MobileNavGroup[] = [];
+
+  const frontMatter = sidebarItems.filter(
+    (i) => i.type === "intro-segment" && i.slug !== "intro-about-the-author",
+  );
+  if (frontMatter.length > 0) {
+    mobileNavGroups.push({
+      title: "Front Matter",
+      items: frontMatter.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/ssr/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
+  const chapterItems = sidebarItems.filter(
+    (i) => i.type === "parent" || i.type === "sub-chapter",
+  );
+  if (chapterItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Chapters",
+      items: chapterItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/ssr/${i.slug}`,
+        type: i.type,
+        parentChapter: i.parentChapter,
+        isParent: i.type === "parent",
+      })),
+    });
+  }
+
+  const backMatter = sidebarItems.filter(
+    (i) => i.slug === "intro-about-the-author",
+  );
+  if (backMatter.length > 0) {
+    mobileNavGroups.push({
+      title: "Back Matter",
+      items: backMatter.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/ssr/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
   return (
     <div className="flex items-center justify-between gap-3">
-      {prev ? (
-        <Link
-          href={`/books/ssr/${prev.slug}`}
-          className={cn(
-            buttonVariants({ variant: "outline", size: "sm" }),
-            "gap-1.5",
-          )}
-        >
-          <ChevronLeft className="size-4" />
-          <span className="hidden sm:inline truncate max-w-[180px]">
-            {prev.label}
-          </span>
-          <span className="sm:hidden">Previous</span>
-        </Link>
-      ) : (
-        <div />
-      )}
+      <div className="flex items-center gap-2">
+        <MobileNav
+          groups={mobileNavGroups}
+          currentSlug={currentSlug}
+          bookTitle="The Science of Self-Realization"
+        />
+        {prev ? (
+          <Link
+            href={`/books/ssr/${prev.slug}`}
+            className={cn(
+              buttonVariants({ variant: "outline", size: "sm" }),
+              "gap-1.5",
+            )}
+          >
+            <ChevronLeft className="size-4" />
+            <span className="hidden sm:inline truncate max-w-[180px]">
+              {prev.label}
+            </span>
+            <span className="sm:hidden">Previous</span>
+          </Link>
+        ) : (
+          <div className="hidden lg:block" />
+        )}
+      </div>
 
       {next ? (
         <Link

app/books/tlc/[chapter]/page.tsx

@@ -11,6 +11,7 @@ import { Card, CardContent } from "@/components/ui/card";
 import { buttonVariants } from "@/components/ui/button";
 import { ChevronLeft, ChevronRight } from "lucide-react";
 import { cn } from "@/lib/utils";
+import { MobileNav, type MobileNavGroup } from "@/components/mobile-nav";
 
 // ---------------------------------------------------------------------------
 // Page
@@ -64,7 +65,12 @@ export default async function TlcChapterPage({
         {/* Main content */}
         <main className="flex-1 min-w-0 px-6 py-8 space-y-8">
           {/* Top navigation */}
-          <TlcNav prev={prev} next={next} />
+          <TlcNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
 
           {/* Content */}
           <Card>
@@ -82,7 +88,12 @@ export default async function TlcChapterPage({
           </Card>
 
           {/* Bottom navigation */}
-          <TlcNav prev={prev} next={next} />
+          <TlcNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
         </main>
       </div>
     </div>
@@ -183,31 +194,70 @@ function SidebarLink({
 function TlcNav({
   prev,
   next,
+  sidebarItems,
+  currentSlug,
 }: {
   prev: TlcSidebarItem | null;
   next: TlcSidebarItem | null;
+  sidebarItems: TlcSidebarItem[];
+  currentSlug: string;
 }) {
+  const mobileNavGroups: MobileNavGroup[] = [];
+
+  const introItems = sidebarItems.filter((i) => i.type === "intro-segment");
+  if (introItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Front Matter",
+      items: introItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/tlc/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
+  const chapterItems = sidebarItems.filter((i) => i.type === "chapter");
+  if (chapterItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Chapters",
+      items: chapterItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/tlc/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
   return (
     <div className="flex items-center justify-between gap-3">
-      {prev ? (
-        <Link
-          href={`/books/tlc/${prev.slug}`}
-          className={cn(
-            buttonVariants({ variant: "outline", size: "sm" }),
-            "gap-1.5",
-          )}
-        >
-          <ChevronLeft className="size-4" />
-          <span className="hidden sm:inline truncate max-w-[180px]">
-            {prev.type === "chapter" && prev.chapter != null
-              ? `Ch. ${prev.chapter}`
-              : prev.label}
-          </span>
-          <span className="sm:hidden">Previous</span>
-        </Link>
-      ) : (
-        <div />
-      )}
+      <div className="flex items-center gap-2">
+        <MobileNav
+          groups={mobileNavGroups}
+          currentSlug={currentSlug}
+          bookTitle="Teachings of Lord Caitanya"
+        />
+        {prev ? (
+          <Link
+            href={`/books/tlc/${prev.slug}`}
+            className={cn(
+              buttonVariants({ variant: "outline", size: "sm" }),
+              "gap-1.5",
+            )}
+          >
+            <ChevronLeft className="size-4" />
+            <span className="hidden sm:inline truncate max-w-[180px]">
+              {prev.type === "chapter" && prev.chapter != null
+                ? `Ch. ${prev.chapter}`
+                : prev.label}
+            </span>
+            <span className="sm:hidden">Previous</span>
+          </Link>
+        ) : (
+          <div className="hidden lg:block" />
+        )}
+      </div>
 
       {next ? (
         <Link

app/books/ttp/[chapter]/page.tsx

@@ -11,6 +11,7 @@ import { Card, CardContent } from "@/components/ui/card";
 import { buttonVariants } from "@/components/ui/button";
 import { ChevronLeft, ChevronRight } from "lucide-react";
 import { cn } from "@/lib/utils";
+import { MobileNav, type MobileNavGroup } from "@/components/mobile-nav";
 
 // ---------------------------------------------------------------------------
 // Page
@@ -64,7 +65,12 @@ export default async function TtpChapterPage({
         {/* Main content */}
         <main className="flex-1 min-w-0 px-6 py-8 space-y-8">
           {/* Top navigation */}
-          <TtpNav prev={prev} next={next} />
+          <TtpNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
 
           {/* Content */}
           <Card>
@@ -82,7 +88,12 @@ export default async function TtpChapterPage({
           </Card>
 
           {/* Bottom navigation */}
-          <TtpNav prev={prev} next={next} />
+          <TtpNav
+            prev={prev}
+            next={next}
+            sidebarItems={sidebarItems}
+            currentSlug={slug}
+          />
         </main>
       </div>
     </div>
@@ -174,31 +185,70 @@ function SidebarLink({
 function TtpNav({
   prev,
   next,
+  sidebarItems,
+  currentSlug,
 }: {
   prev: TtpSidebarItem | null;
   next: TtpSidebarItem | null;
+  sidebarItems: TtpSidebarItem[];
+  currentSlug: string;
 }) {
+  const mobileNavGroups: MobileNavGroup[] = [];
+
+  const introItems = sidebarItems.filter((i) => i.type === "intro-segment");
+  if (introItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Front Matter",
+      items: introItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/ttp/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
+  const chapterItems = sidebarItems.filter((i) => i.type === "chapter");
+  if (chapterItems.length > 0) {
+    mobileNavGroups.push({
+      title: "Chapters",
+      items: chapterItems.map((i) => ({
+        slug: i.slug,
+        label: i.label,
+        href: `/books/ttp/${i.slug}`,
+        type: i.type,
+      })),
+    });
+  }
+
   return (
     <div className="flex items-center justify-between gap-3">
-      {prev ? (
-        <Link
-          href={`/books/ttp/${prev.slug}`}
-          className={cn(
-            buttonVariants({ variant: "outline", size: "sm" }),
-            "gap-1.5",
-          )}
-        >
-          <ChevronLeft className="size-4" />
-          <span className="hidden sm:inline truncate max-w-[180px]">
-            {prev.type === "chapter" && prev.chapter != null
-              ? `Ch. ${prev.chapter}`
-              : prev.label}
-          </span>
-          <span className="sm:hidden">Previous</span>
-        </Link>
-      ) : (
-        <div />
-      )}
+      <div className="flex items-center gap-2">
+        <MobileNav
+          groups={mobileNavGroups}
+          currentSlug={currentSlug}
+          bookTitle="Transcendental Teachings of Prahlāda Mahārāja"
+        />
+        {prev ? (
+          <Link
+            href={`/books/ttp/${prev.slug}`}
+            className={cn(
+              buttonVariants({ variant: "outline", size: "sm" }),
+              "gap-1.5",
+            )}
+          >
+            <ChevronLeft className="size-4" />
+            <span className="hidden sm:inline truncate max-w-[180px]">
+              {prev.type === "chapter" && prev.chapter != null
+                ? `Ch. ${prev.chapter}`
+                : prev.label}
+            </span>
+            <span className="sm:hidden">Previous</span>
+          </Link>
+        ) : (
+          <div className="hidden lg:block" />
+        )}
+      </div>
 
       {next ? (
         <Link