Fix theme consistency, i18n completeness, CSS variable naming, and hardcoded strings

src/app/admin/vpn/page.tsx

@@ -80,7 +80,7 @@ export default async function AdminVpn({
             </label>
           </div>
 
-          <div className="grid cols-2">
+          <div className="grid grid-cols-1 gap-4 md:grid-cols-2">
             <div>
               <label
                 htmlFor="vpn_provider"