feat: refine letters UI

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

@@ -43,7 +43,7 @@ export default async function MgChapterPage({
 
   return (
     <div className="min-h-screen bg-background">
-      <PageHeader sticky wide>
+      <PageHeader sticky>
         <Link
           href="/books/mg"
           className="text-sm text-muted-foreground hover:text-foreground transition-colors"
@@ -58,7 +58,7 @@ export default async function MgChapterPage({
         </h1>
       </PageHeader>
 
-      <div className="w-full md:max-w-6xl mx-auto flex">
+      <div className="max-w-5xl mx-auto flex">
         {/* Left sidebar */}
         <MgSidebar items={sidebarItems} currentSlug={slug} />