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

src/app/admin/radio/settings/page.tsx

@@ -279,7 +279,7 @@ export default async function AdminRadioSettingsPage() {
         {groups.map((group) => (
           <section key={group.title} className="admin-card" style={{ marginBottom: '1.25rem' }}>
             <h2 style={{ marginTop: 0 }}>{group.title}</h2>
-            <div className="grid cols-2">
+            <div className="grid grid-cols-1 gap-4 md:grid-cols-2">
               {group.fields.map((field) => (
                 <div key={field.key}>
                   <label