feat: refine letters UI

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

@@ -36,7 +36,7 @@ export default async function VaChapterPage({
 
   return (
     <div className="min-h-screen bg-background">
-      <PageHeader sticky wide>
+      <PageHeader sticky>
         <Link
           href="/books/va"
           className="text-sm text-muted-foreground hover:text-foreground transition-colors"
@@ -48,7 +48,7 @@ export default async function VaChapterPage({
         </h1>
       </PageHeader>
 
-      <div className="w-full md:max-w-6xl mx-auto flex">
+      <div className="max-w-5xl mx-auto flex">
         <VaSidebar items={sidebarItems} currentSlug={slug} />
 
         <main className="flex-1 min-w-0 px-6 py-8 space-y-8">