* { margin: 0; padding: 0; box-sizing: border-box; }
:root {
  --primary: #4A7FD4;
  --primary-dark: #3A6BBF;
  --primary-light: #EBF2FF;
  --success: #52C41A;
  --warning: #FAAD14;
  --danger: #EA6668;
  --text: #1A1B1C;
  --text-secondary: #6B7280;
  --bg: #F4F3EE;
  --card: #FFFFFF;
  --border: #E4E3DD;
  --radius: 12px;
  --shadow: 0 2px 8px rgba(0,0,0,0.06);
}
body { font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif; background: var(--bg); color: var(--text); line-height: 1.6; }
.hidden { display: none !important; }

/* 导航 */
.navbar { display: flex; align-items: center; justify-content: space-between; padding: 0 24px; height: 60px; background: var(--card); border-bottom: 1px solid var(--border); position: sticky; top: 0; z-index: 100; box-shadow: var(--shadow); }
.nav-left { display: flex; align-items: center; gap: 24px; }
.nav-logo { font-size: 20px; font-weight: 700; color: var(--primary); cursor: pointer; }
.nav-links { display: flex; gap: 4px; }
.nav-links a { padding: 8px 14px; border-radius: 8px; color: var(--text-secondary); text-decoration: none; font-size: 14px; cursor: pointer; transition: all 0.2s; }
.nav-links a:hover, .nav-links a.active { background: var(--primary-light); color: var(--primary); }
.nav-right { display: flex; align-items: center; gap: 12px; }
.user-info { font-size: 14px; color: var(--text-secondary); }
.nav-toggle { display: none; background: none; border: none; font-size: 24px; cursor: pointer; color: var(--text); }
.mobile-menu { position: fixed; top: 60px; left: 0; right: 0; background: var(--card); border-bottom: 1px solid var(--border); padding: 12px; z-index: 99; box-shadow: var(--shadow); }
.mobile-menu a { display: block; padding: 12px 16px; border-radius: 8px; color: var(--text); text-decoration: none; font-size: 15px; }
.mobile-menu a:hover { background: var(--primary-light); }

/* 按钮 */
.btn { padding: 10px 20px; border-radius: 8px; border: none; font-size: 14px; font-weight: 500; cursor: pointer; transition: all 0.2s; display: inline-flex; align-items: center; gap: 6px; }
.btn-primary { background: var(--primary); color: white; }
.btn-primary:hover { background: var(--primary-dark); }
.btn-success { background: var(--success); color: white; }
.btn-warning { background: var(--warning); color: white; }
.btn-danger { background: var(--danger); color: white; }
.btn-ghost { background: transparent; color: var(--text-secondary); border: 1px solid var(--border); }
.btn-ghost:hover { background: var(--bg); }
.btn-sm { padding: 6px 12px; font-size: 13px; }
.btn-block { width: 100%; justify-content: center; }
.btn:disabled { opacity: 0.5; cursor: not-allowed; }

/* 主内容 */
.main-content { max-width: 1200px; margin: 0 auto; padding: 24px; min-height: calc(100vh - 60px); }

/* 卡片 */
.card { background: var(--card); border-radius: var(--radius); padding: 20px; box-shadow: var(--shadow); margin-bottom: 16px; }
.card-title { font-size: 18px; font-weight: 600; margin-bottom: 16px; display: flex; align-items: center; justify-content: space-between; }

/* 网格 */
.grid { display: grid; gap: 16px; }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }
.grid-6 { grid-template-columns: repeat(6, 1fr); }

/* KPI 卡片 */
.kpi-card { background: var(--card); border-radius: var(--radius); padding: 20px; box-shadow: var(--shadow); border-left: 4px solid var(--primary); }
.kpi-label { font-size: 13px; color: var(--text-secondary); margin-bottom: 8px; }
.kpi-value { font-size: 28px; font-weight: 700; color: var(--text); }
.kpi-sub { font-size: 12px; color: var(--text-secondary); margin-top: 4px; }

/* 登录页 */
.login-page { display: flex; align-items: center; justify-content: center; min-height: 100vh; background: linear-gradient(135deg, #667eea 0%, #764ba2 100%); padding: 20px; }
.login-box { background: var(--card); border-radius: 16px; padding: 40px; width: 100%; max-width: 420px; box-shadow: 0 20px 60px rgba(0,0,0,0.2); }
.login-title { font-size: 28px; font-weight: 700; text-align: center; margin-bottom: 8px; color: var(--text); }
.login-subtitle { text-align: center; color: var(--text-secondary); margin-bottom: 32px; font-size: 14px; }
.form-group { margin-bottom: 20px; }
.form-label { display: block; font-size: 14px; font-weight: 500; margin-bottom: 8px; color: var(--text); }
.form-input { width: 100%; padding: 12px 16px; border: 1px solid var(--border); border-radius: 8px; font-size: 14px; transition: border-color 0.2s; outline: none; }
.form-input:focus { border-color: var(--primary); box-shadow: 0 0 0 3px rgba(74,127,212,0.1); }
.form-select { width: 100%; padding: 12px 16px; border: 1px solid var(--border); border-radius: 8px; font-size: 14px; background: white; outline: none; }
.login-tabs { display: flex; gap: 0; margin-bottom: 24px; border-bottom: 2px solid var(--border); }
.login-tab { flex: 1; padding: 12px; text-align: center; cursor: pointer; font-size: 15px; font-weight: 500; color: var(--text-secondary); border-bottom: 2px solid transparent; margin-bottom: -2px; transition: all 0.2s; }
.login-tab.active { color: var(--primary); border-bottom-color: var(--primary); }
.login-footer { text-align: center; margin-top: 24px; font-size: 13px; color: var(--text-secondary); }
.login-footer a { color: var(--primary); cursor: pointer; text-decoration: none; }

/* 语言卡片 */
.lang-card { background: var(--card); border-radius: var(--radius); padding: 24px; box-shadow: var(--shadow); cursor: pointer; transition: all 0.3s; text-align: center; border-top: 4px solid var(--primary); }
.lang-card:hover { transform: translateY(-4px); box-shadow: 0 8px 24px rgba(0,0,0,0.12); }
.lang-flag { font-size: 48px; margin-bottom: 12px; }
.lang-name { font-size: 18px; font-weight: 600; margin-bottom: 4px; }
-lang-native { font-size: 14px; color: var(--text-secondary); }
.lang-courses { font-size: 12px; color: var(--text-secondary); margin-top: 8px; }

/* 课程卡片 */
.course-card { background: var(--card); border-radius: var(--radius); padding: 20px; box-shadow: var(--shadow); cursor: pointer; transition: all 0.2s; border-left: 4px solid var(--primary); }
.course-card:hover { transform: translateX(4px); }
.course-level { display: inline-block; padding: 2px 10px; border-radius: 12px; font-size: 12px; font-weight: 500; margin-bottom: 8px; }
.level-beginner { background: #E6F7FF; color: #1890FF; }
.level-elementary { background: #F6FFED; color: #52C41A; }
.level-intermediate { background: #FFF7E6; color: #FA8C16; }
.level-advanced { background: #FFF1F0; color: #F5222D; }
.course-title { font-size: 16px; font-weight: 600; margin-bottom: 8px; }
.course-desc { font-size: 13px; color: var(--text-secondary); margin-bottom: 12px; }
.course-meta { display: flex; gap: 16px; font-size: 12px; color: var(--text-secondary); }

/* 课时列表 */
.lesson-item { display: flex; align-items: center; padding: 16px; background: var(--card); border-radius: 8px; margin-bottom: 8px; cursor: pointer; transition: all 0.2s; border: 1px solid transparent; }
.lesson-item:hover { border-color: var(--primary); background: var(--primary-light); }
.lesson-num { width: 36px; height: 36px; border-radius: 50%; background: var(--primary-light); color: var(--primary); display: flex; align-items: center; justify-content: center; font-weight: 600; margin-right: 16px; flex-shrink: 0; }
.lesson-info { flex: 1; }
.lesson-title { font-size: 15px; font-weight: 500; margin-bottom: 2px; }
.lesson-desc { font-size: 13px; color: var(--text-secondary); }
.lesson-duration { font-size: 13px; color: var(--text-secondary); }

/* 学习模块 */
.module-tabs { display: flex; gap: 8px; margin-bottom: 20px; flex-wrap: wrap; }
.module-tab { padding: 10px 20px; border-radius: 8px; background: var(--card); border: 1px solid var(--border); cursor: pointer; font-size: 14px; font-weight: 500; transition: all 0.2s; }
.module-tab.active { background: var(--primary); color: white; border-color: var(--primary); }
.module-tab:hover:not(.active) { border-color: var(--primary); color: var(--primary); }

/* 单词卡片 */
.word-card { background: var(--card); border-radius: 16px; padding: 40px; text-align: center; box-shadow: var(--shadow); margin-bottom: 20px; }
.word-text { font-size: 36px; font-weight: 700; margin-bottom: 8px; color: var(--text); }
.word-pron { font-size: 18px; color: var(--text-secondary); margin-bottom: 16px; }
.word-translation { font-size: 20px; color: var(--primary); margin-bottom: 20px; }
.word-actions { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; }

/* 语法题 */
.grammar-question { font-size: 18px; margin-bottom: 20px; line-height: 1.8; }
.grammar-options { display: flex; flex-direction: column; gap: 10px; }
.grammar-option { padding: 14px 20px; border: 2px solid var(--border); border-radius: 8px; cursor: pointer; font-size: 15px; transition: all 0.2s; }
.grammar-option:hover { border-color: var(--primary); }
.grammar-option.selected { border-color: var(--primary); background: var(--primary-light); }
.grammar-option.correct { border-color: var(--success); background: #F6FFED; }
.grammar-option.wrong { border-color: var(--danger); background: #FFF1F0; }
.grammar-explanation { margin-top: 16px; padding: 16px; background: var(--primary-light); border-radius: 8px; font-size: 14px; color: var(--text); }

/* 听力 */
.listening-card { text-align: center; padding: 40px; }
.listening-play-btn { width: 80px; height: 80px; border-radius: 50%; background: var(--primary); color: white; border: none; font-size: 32px; cursor: pointer; margin: 0 auto 20px; display: flex; align-items: center; justify-content: center; transition: all 0.2s; }
.listening-play-btn:hover { transform: scale(1.1); }

/* 口语 */
.speaking-card { text-align: center; padding: 40px; }
.speaking-record-btn { width: 80px; height: 80px; border-radius: 50%; background: var(--danger); color: white; border: none; font-size: 28px; cursor: pointer; margin: 0 auto 20px; display: flex; align-items: center; justify-content: center; }
.speaking-record-btn.recording { animation: pulse 1s infinite; }
@keyframes pulse { 0%,100% { transform: scale(1); } 50% { transform: scale(1.1); } }

/* 进度 */
.progress-bar { height: 8px; background: var(--border); border-radius: 4px; overflow: hidden; margin: 8px 0; }
.progress-fill { height: 100%; background: var(--primary); border-radius: 4px; transition: width 0.3s; }
.progress-stats { display: flex; gap: 24px; flex-wrap: wrap; }
.progress-stat { text-align: center; }
.progress-stat-value { font-size: 24px; font-weight: 700; color: var(--primary); }
.progress-stat-label { font-size: 12px; color: var(--text-secondary); }

/* 成就 */
.achievement-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(140px, 1fr)); gap: 16px; }
.achievement-item { text-align: center; padding: 20px 12px; background: var(--card); border-radius: var(--radius); box-shadow: var(--shadow); }
.achievement-item.locked { opacity: 0.4; filter: grayscale(1); }
.achievement-icon { font-size: 40px; margin-bottom: 8px; }
.achievement-name { font-size: 14px; font-weight: 600; margin-bottom: 4px; }
.achievement-desc { font-size: 11px; color: var(--text-secondary); }

/* 社区 */
.post-item { background: var(--card); border-radius: var(--radius); padding: 20px; margin-bottom: 12px; box-shadow: var(--shadow); cursor: pointer; transition: all 0.2s; }
.post-item:hover { transform: translateY(-2px); }
.post-header { display: flex; align-items: center; gap: 12px; margin-bottom: 12px; }
.post-avatar { width: 40px; height: 40px; border-radius: 50%; background: var(--primary-light); color: var(--primary); display: flex; align-items: center; justify-content: center; font-weight: 600; flex-shrink: 0; }
.post-author { font-size: 14px; font-weight: 500; }
.post-time { font-size: 12px; color: var(--text-secondary); }
.post-title { font-size: 16px; font-weight: 600; margin-bottom: 8px; }
.post-content { font-size: 14px; color: var(--text-secondary); margin-bottom: 12px; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; }
.post-meta { display: flex; gap: 20px; font-size: 13px; color: var(--text-secondary); }
.post-meta span { display: flex; align-items: center; gap: 4px; cursor: pointer; }
.post-meta span:hover { color: var(--primary); }

/* 评论 */
.comment-item { display: flex; gap: 12px; padding: 12px 0; border-bottom: 1px solid var(--border); }
.comment-avatar { width: 32px; height: 32px; border-radius: 50%; background: var(--primary-light); color: var(--primary); display: flex; align-items: center; justify-content: center; font-size: 13px; font-weight: 600; flex-shrink: 0; }
.comment-content { flex: 1; }
.comment-author { font-size: 13px; font-weight: 500; margin-bottom: 2px; }
.comment-text { font-size: 14px; color: var(--text); }
.comment-time { font-size: 11px; color: var(--text-secondary); margin-top: 4px; }

/* 表格 */
.table { width: 100%; border-collapse: collapse; }
.table th { text-align: left; padding: 12px 16px; background: var(--bg); font-size: 13px; font-weight: 600; color: var(--text-secondary); border-bottom: 2px solid var(--border); }
.table td { padding: 12px 16px; font-size: 14px; border-bottom: 1px solid var(--border); }
.table tr:hover { background: var(--bg); }
.badge { display: inline-block; padding: 2px 10px; border-radius: 12px; font-size: 12px; font-weight: 500; }
.badge-active { background: #F6FFED; color: #52C41A; }
.badge-inactive { background: #FFF1F0; color: #F5222D; }
.badge-trial { background: #FFF7E6; color: #FA8C16; }
.badge-monthly { background: #E6F7FF; color: #1890FF; }
.badge-yearly { background: #F9F0FF; color: #722ED1; }

/* 音频播放器 */
.audio-player { position: fixed; bottom: 20px; left: 50%; transform: translateX(-50%); background: var(--text); color: white; padding: 12px 24px; border-radius: 24px; display: flex; align-items: center; gap: 12px; box-shadow: 0 4px 20px rgba(0,0,0,0.3); z-index: 200; }
.audio-player button { background: none; border: none; color: white; cursor: pointer; font-size: 16px; }

/* Toast */
.toast { position: fixed; top: 80px; left: 50%; transform: translateX(-50%); background: var(--text); color: white; padding: 12px 24px; border-radius: 8px; font-size: 14px; z-index: 300; box-shadow: 0 4px 12px rgba(0,0,0,0.2); animation: slideDown 0.3s; }
@keyframes slideDown { from { transform: translateX(-50%) translateY(-20px); opacity: 0; } to { transform: translateX(-50%) translateY(0); opacity: 1; } }

/* 标签页 */
.tabs { display: flex; gap: 0; border-bottom: 2px solid var(--border); margin-bottom: 20px; }
.tab { padding: 12px 20px; cursor: pointer; font-size: 14px; font-weight: 500; color: var(--text-secondary); border-bottom: 2px solid transparent; margin-bottom: -2px; transition: all 0.2s; }
.tab.active { color: var(--primary); border-bottom-color: var(--primary); }

/* 空状态 */
.empty-state { text-align: center; padding: 60px 20px; color: var(--text-secondary); }
.empty-icon { font-size: 64px; margin-bottom: 16px; }

/* 响应式 */
@media (max-width: 768px) {
  .navbar { padding: 0 16px; }
  .nav-links { display: none; }
  .nav-toggle { display: block; }
  .user-info { display: none; }
  .main-content { padding: 16px; }
  .grid-2, .grid-3, .grid-4, .grid-6 { grid-template-columns: 1fr; }
  .login-box { padding: 24px; }
  .word-card { padding: 24px 16px; }
  .word-text { font-size: 28px; }
  .kpi-value { font-size: 22px; }
  .table { font-size: 12px; }
  .table th, .table td { padding: 8px; }
  .module-tabs { overflow-x: auto; flex-wrap: nowrap; }
  .module-tab { white-space: nowrap; flex-shrink: 0; }
}
@media (max-width: 480px) {
  .achievement-grid { grid-template-columns: repeat(2, 1fr); }
}