feat: 폼 유효성 피드백 + 모바일 반응형

폼 검증:
- RegisterPage: 아이디 실시간 검증, 비밀번호 강도, 확인 일치
- LoginPage: aria-describedby 접근성 개선

반응형:
- 768px 이하 레이아웃 최적화, 터치 타겟 44px

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/components/admin/AdminCommon.css

@@ -305,3 +305,57 @@
   background: rgba(255, 255, 255, 0.08);
   color: rgba(255, 255, 255, 0.45);
 }
+
+/* Mobile responsive */
+@media (max-width: 768px) {
+  .admin-form {
+    padding: 16px 12px;
+  }
+
+  .admin-input,
+  .admin-textarea {
+    width: 100%;
+    box-sizing: border-box;
+  }
+
+  .admin-list-item {
+    flex-direction: column;
+    align-items: flex-start;
+    gap: 8px;
+    padding: 10px 12px;
+  }
+
+  .admin-list-info {
+    width: 100%;
+  }
+
+  .admin-list-actions {
+    width: 100%;
+    justify-content: flex-end;
+  }
+
+  .admin-form-actions {
+    flex-direction: column;
+  }
+
+  .admin-form-actions button {
+    width: 100%;
+    min-height: 44px;
+  }
+
+  .btn-admin-primary,
+  .btn-admin-secondary,
+  .btn-admin-edit,
+  .btn-admin-delete {
+    min-height: 44px;
+  }
+
+  .admin-meta-row {
+    flex-direction: column;
+  }
+
+  .admin-deploy-header {
+    flex-direction: column;
+    align-items: flex-start;
+  }
+}

src/pages/AdminPage.css

@@ -95,3 +95,43 @@
   margin: 0 auto;
   padding: 32px 24px 80px;
 }
+
+/* Mobile responsive */
+@media (max-width: 768px) {
+  .admin-header {
+    flex-direction: column;
+    gap: 12px;
+    padding: 12px 16px;
+  }
+
+  .admin-header-left {
+    width: 100%;
+    justify-content: center;
+  }
+
+  .admin-header-right {
+    width: 100%;
+    justify-content: center;
+  }
+
+  .admin-tabs {
+    padding: 12px 16px 0;
+    overflow-x: auto;
+    -webkit-overflow-scrolling: touch;
+    scrollbar-width: none;
+  }
+
+  .admin-tabs::-webkit-scrollbar {
+    display: none;
+  }
+
+  .admin-tab {
+    white-space: nowrap;
+    flex-shrink: 0;
+    min-height: 44px;
+  }
+
+  .admin-main {
+    padding: 20px 12px 60px;
+  }
+}

src/pages/AuthPage.css

@@ -165,12 +165,65 @@
   color: rgba(255, 255, 255, 0.7);
 }
 
-.password-strength {
-  font-size: 0.8rem;
-  color: rgba(186, 205, 176, 0.7);
-  margin: -12px 0 0;
+/* Validation feedback */
+.input-hint {
+  font-size: 0.75rem;
+  color: #888;
+  margin-top: 2px;
 }
 
-.password-strength.strength-weak {
+.input-hint-error {
   color: #e57373;
 }
+
+.input-hint-success {
+  color: #bacdb0;
+}
+
+.input-group input.input-valid {
+  border-color: #bacdb0 !important;
+}
+
+.input-group input.input-invalid {
+  border-color: #e57373 !important;
+}
+
+.password-strength {
+  font-size: 0.75rem;
+  margin-top: 2px;
+}
+
+.strength-weak {
+  color: #e57373;
+}
+
+.strength-medium {
+  color: #ffd54f;
+}
+
+.strength-strong {
+  color: #bacdb0;
+}
+
+/* Mobile responsive */
+@media (max-width: 768px) {
+  .login-panel {
+    max-width: 100%;
+    padding: 32px 20px;
+    margin: 0 12px;
+    border-radius: 8px;
+  }
+
+  .game-title {
+    font-size: 2.2rem;
+  }
+
+  .login-header {
+    margin-bottom: 28px;
+  }
+
+  .btn-login,
+  .btn-ssafy {
+    min-height: 44px;
+  }
+}

src/pages/HomePage.css

@@ -124,3 +124,43 @@
   margin: 0 auto;
   padding: 40px 24px 80px;
 }
+
+/* Mobile responsive */
+@media (max-width: 768px) {
+  .home-header {
+    flex-direction: column;
+    gap: 12px;
+    padding: 12px 16px;
+    text-align: center;
+  }
+
+  .home-user {
+    width: 100%;
+    justify-content: center;
+  }
+
+  .hero-banner {
+    height: 180px;
+  }
+
+  .hero-title {
+    font-size: 1.8rem;
+  }
+
+  .hero-desc {
+    font-size: 0.85rem;
+  }
+
+  .home-main {
+    padding: 24px 16px 60px;
+  }
+
+  .btn-logout,
+  .btn-admin-link,
+  .btn-header-login {
+    min-height: 44px;
+    display: inline-flex;
+    align-items: center;
+    justify-content: center;
+  }
+}

src/pages/LoginPage.jsx

@@ -51,6 +51,7 @@ export default function LoginPage() {
               placeholder="아이디를 입력하세요"
               autoComplete="username"
               maxLength={50}
+              aria-describedby={error ? 'login-error' : undefined}
             />
           </div>
 
@@ -64,11 +65,12 @@ export default function LoginPage() {
               placeholder="비밀번호를 입력하세요"
               autoComplete="current-password"
               maxLength={72}
+              aria-describedby={error ? 'login-error' : undefined}
             />
           </div>
 
           {justRegistered && <p className="login-success">회원가입이 완료되었습니다. 로그인해주세요.</p>}
-          {error && <p className="login-error" role="alert">{error}</p>}
+          {error && <p id="login-error" className="login-error" role="alert">{error}</p>}
 
           <button type="submit" className="btn-login" disabled={loading}>
             {loading ? '로그인 중...' : '로그인'}

src/pages/RegisterPage.jsx

@@ -3,29 +3,31 @@ import { useNavigate, Link } from 'react-router-dom';
 import { register } from '../api/auth';
 import './AuthPage.css';
 
+const USERNAME_REGEX = /^[a-z0-9_-]{3,50}$/;
+
 export default function RegisterPage() {
   const [username, setUsername] = useState('');
   const [password, setPassword] = useState('');
   const [confirm, setConfirm] = useState('');
   const [error, setError] = useState('');
   const [loading, setLoading] = useState(false);
+  const [usernameTouched, setUsernameTouched] = useState(false);
   const navigate = useNavigate();
 
+  const isUsernameValid = USERNAME_REGEX.test(username);
+  const showUsernameError = usernameTouched && username.length > 0 && !isUsernameValid;
+  const showUsernameValid = usernameTouched && username.length > 0 && isUsernameValid;
+
   const getPasswordStrength = (pw) => {
-    if (pw.length === 0) return '';
-    if (pw.length < 6) return '비밀번호는 6자 이상이어야 합니다.';
-    let strength = 0;
-    if (/[a-z]/.test(pw)) strength++;
-    if (/[A-Z]/.test(pw)) strength++;
-    if (/[0-9]/.test(pw)) strength++;
-    if (/[^a-zA-Z0-9]/.test(pw)) strength++;
-    if (strength <= 1) return '약함';
-    if (strength <= 2) return '보통';
-    return '강함';
+    if (pw.length === 0) return { label: '', level: '' };
+    if (pw.length < 6) return { label: '약함', level: 'weak' };
+    if (pw.length < 10) return { label: '중간', level: 'medium' };
+    return { label: '강함', level: 'strong' };
   };
 
   const passwordStrength = getPasswordStrength(password);
-  const isPasswordWeak = password.length > 0 && password.length < 6;
+  const confirmMismatch = confirm.length > 0 && password !== confirm;
+  const confirmMatch = confirm.length > 0 && password === confirm;
 
   const handleSubmit = async (e) => {
     e.preventDefault();
@@ -80,10 +82,17 @@ export default function RegisterPage() {
               type="text"
               value={username}
               onChange={(e) => setUsername(e.target.value)}
+              onBlur={() => setUsernameTouched(true)}
               placeholder="아이디를 입력하세요"
               autoComplete="username"
               maxLength={50}
+              className={showUsernameValid ? 'input-valid' : showUsernameError ? 'input-invalid' : ''}
+              aria-describedby="username-hint"
             />
+            <span id="username-hint" className={`input-hint ${showUsernameError ? 'input-hint-error' : ''}`}>
+              {showUsernameError ? '3~50자 영문 소문자, 숫자, _, -만 가능합니다' : '3~50자 영문 소문자, 숫자, _, -만 가능'}
+              {showUsernameValid && ' \u2713'}
+            </span>
           </div>
 
           <div className="input-group">
@@ -96,15 +105,15 @@ export default function RegisterPage() {
               placeholder="6자 이상 입력하세요"
               autoComplete="new-password"
               maxLength={72}
+              aria-describedby="password-strength"
             />
+            {passwordStrength.label && (
+              <span id="password-strength" className={`password-strength strength-${passwordStrength.level}`}>
+                강도: {passwordStrength.label}
+              </span>
+            )}
           </div>
 
-          {passwordStrength && (
-            <p className={`password-strength ${isPasswordWeak ? 'strength-weak' : ''}`}>
-              강도: {passwordStrength}
-            </p>
-          )}
-
           <div className="input-group">
             <label htmlFor="confirm">비밀번호 확인</label>
             <input
@@ -115,7 +124,15 @@ export default function RegisterPage() {
               placeholder="비밀번호를 다시 입력하세요"
               autoComplete="new-password"
               maxLength={72}
+              className={confirmMatch ? 'input-valid' : confirmMismatch ? 'input-invalid' : ''}
+              aria-describedby="confirm-hint"
             />
+            {confirmMismatch && (
+              <span id="confirm-hint" className="input-hint input-hint-error">비밀번호가 일치하지 않습니다</span>
+            )}
+            {confirmMatch && (
+              <span id="confirm-hint" className="input-hint input-hint-success">비밀번호가 일치합니다 \u2713</span>
+            )}
           </div>
 
           {error && <p className="login-error" role="alert">{error}</p>}