feat(classes): optimize teacher dashboard ui and implement grade management

src/app/(dashboard)/teacher/textbooks/page.tsx

@@ -33,7 +33,7 @@ async function TextbooksResults({ searchParams }: { searchParams: Promise<Search
         title={hasFilters ? "No textbooks match your filters" : "No textbooks yet"}
         description={hasFilters ? "Try clearing filters or adjusting keywords." : "Create your first textbook to start organizing chapters."}
         action={hasFilters ? { label: "Clear filters", href: "/teacher/textbooks" } : undefined}
-        className="bg-card"
+        className="min-h-[400px] border-muted-foreground/10"
       />
     )
   }
@@ -50,7 +50,7 @@ async function TextbooksResults({ searchParams }: { searchParams: Promise<Search
 export default async function TextbooksPage({ searchParams }: { searchParams: Promise<SearchParams> }) {
 
   return (
-    <div className="space-y-6">
+    <div className="space-y-6 p-8">
       {/* Page Header */}
       <div className="flex flex-col gap-4 md:flex-row md:items-center md:justify-between">
         <div>