Tighten ultrawide layout with visible side gutters.

Cap content at 768-960px via PageShell width tiers, add muted outer margins, and limit gua grid to four columns.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/learn/other/page.tsx

@@ -2,7 +2,6 @@ import Link from "next/link";
 import PageShell from "@/components/page-shell";
 import { GuaGrid } from "@/components/learn/gua-grid";
 import { ZenCard } from "@/components/ui/zen-card";
-import { APP_CONTAINER } from "@/lib/layout";
 import {
   getGuaName,
   guaNumFromMark,
@@ -18,7 +17,7 @@ export default async function LearnOtherPage() {
   }));
 
   return (
-    <PageShell className={`${APP_CONTAINER} py-8`}>
+    <PageShell className="py-8">
       <div className="mb-8 text-center">
         <h1 className="text-2xl font-bold tracking-wide">易经学习</h1>
         <p className="mt-2 text-sm text-muted-foreground">