refactor(styles): establish shared design system

src/views/system/ForbiddenView.vue

@@ -4,12 +4,12 @@ import { RouterLink } from 'vue-router'
 </script>
 
 <template>
-  <div class="flex min-h-[calc(100vh-4rem)] items-center justify-center px-4 py-10">
-    <div class="w-full max-w-2xl border border-slate-200 bg-white px-8 py-14 text-center shadow-sm">
+  <div class="oc-system-page">
+    <div class="oc-system-card">
       <div class="text-7xl leading-none">🖐️</div>
       <p class="mt-6 text-sm font-medium uppercase tracking-[0.24em] text-rose-600">403 Forbidden</p>
-      <h1 class="mt-3 text-4xl font-bold text-slate-900">这里不让进</h1>
-      <p class="mx-auto mt-4 max-w-xl text-sm leading-7 text-slate-600">
+      <h1 class="oc-page-title">这里不让进</h1>
+      <p class="oc-page-description mx-auto max-w-xl">
         你当前没有访问这个页面的权限。通常是因为这个区域只对管理员开放。
       </p>