전체적인 스타일 수정

frontend/components/admin/UserManagement.tsx

@@ -101,14 +101,18 @@ export function UserManagement() {
 
       {/* 에러 메시지 */}
       {error && (
-        <div className="bg-destructive/10 border-destructive/20 rounded-lg border p-4">
+        <div className="rounded-lg border border-destructive/50 bg-destructive/10 p-4">
           <div className="flex items-center justify-between">
-            <p className="text-destructive font-medium">오류가 발생했습니다</p>
-            <button onClick={clearError} className="text-destructive hover:text-destructive/80">
+            <p className="text-sm font-semibold text-destructive">오류가 발생했습니다</p>
+            <button
+              onClick={clearError}
+              className="text-destructive transition-colors hover:text-destructive/80"
+              aria-label="에러 메시지 닫기"
+            >
               ✕
             </button>
           </div>
-          <p className="text-destructive/80 mt-1">{error}</p>
+          <p className="mt-1.5 text-sm text-destructive/80">{error}</p>
         </div>
       )}