/* ═══════════════════════════════════════════════════════════
   自由刷题室 (FreeQuiz) — 主样式表
   ═══════════════════════════════════════════════════════════ */

/* ── CSS 变量（主题系统） ── */
:root {
  --font-size: 16px;
  --radius: 12px;
  --radius-sm: 8px;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="light"] {
  --bg: #f0f2f5;
  --bg-card: #ffffff;
  --bg-nav: #ffffff;
  --bg-hover: #e8ecf1;
  --text: #1a2332;
  --text-secondary: #6b7a8f;
  --text-muted: #a0adb8;
  --primary: #4a6fa5;
  --primary-hover: #3a5a8a;
  --primary-light: #e3edf7;
  --success: #2d8f5c;
  --success-light: #e6f7ee;
  --danger: #d9534f;
  --danger-light: #fde8e8;
  --warning: #e6a817;
  --warning-light: #fef8e0;
  --border: #dce1e8;
  --shadow: 0 1px 8px rgba(0,0,0,0.07), 0 2px 16px rgba(0,0,0,0.04);
  --shadow-lg: 0 4px 20px rgba(0,0,0,0.10), 0 8px 32px rgba(0,0,0,0.06);
  --gradient-primary: linear-gradient(135deg, #4a6fa5, #6b8fc5);
  --gradient-success: linear-gradient(135deg, #2d8f5c, #4ab87a);
  --gradient-danger: linear-gradient(135deg, #d9534f, #e87a77);
}

[data-theme="dark"] {
  --bg: #13141f;
  --bg-card: #1e1f32;
  --bg-nav: #18192b;
  --bg-hover: #282a45;
  --text: #e2e4ed;
  --text-secondary: #9496b0;
  --text-muted: #5e6080;
  --primary: #6b9fd8;
  --primary-hover: #82b0e0;
  --primary-light: #262a50;
  --success: #4cc38a;
  --success-light: #1e3535;
  --danger: #e86363;
  --danger-light: #332a35;
  --warning: #e8b339;
  --warning-light: #35321e;
  --border: #2d2f4a;
  --shadow: 0 1px 8px rgba(0,0,0,0.25), 0 2px 16px rgba(0,0,0,0.15);
  --shadow-lg: 0 4px 20px rgba(0,0,0,0.35), 0 8px 32px rgba(0,0,0,0.2);
  --gradient-primary: linear-gradient(135deg, #4a6fa5, #3a5a8a);
  --gradient-success: linear-gradient(135deg, #2d8f5c, #236e48);
  --gradient-danger: linear-gradient(135deg, #d9534f, #b04340);
}

/* ── 全局重置 ── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html {
  font-size: var(--font-size);
  -webkit-tap-highlight-color: transparent;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
  transition: background var(--transition), color var(--transition);
}

a { color: var(--primary); text-decoration: none; }
a:hover { color: var(--primary-hover); }

/* ── 导航栏 ── */
.navbar {
  background: var(--bg-nav);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  transition: background var(--transition), border-color var(--transition);
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 20px;
  height: 58px;
}

.nav-brand {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text) !important;
  white-space: nowrap;
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--text);
  padding: 4px 10px;
  border-radius: var(--radius-sm);
}
.nav-toggle:hover { background: var(--bg-hover); }

.nav-menu {
  display: flex;
  list-style: none;
  gap: 2px;
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 20px 10px;
  flex-wrap: wrap;
}

.nav-menu li a {
  display: flex;
  align-items: center;
  gap: 5px;
  padding: 8px 16px;
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  font-size: 0.9rem;
  transition: all var(--transition);
  white-space: nowrap;
}
.nav-menu li a:hover { background: var(--bg-hover); color: var(--text); }
.nav-menu li a.active {
  background: var(--primary-light);
  color: var(--primary);
  font-weight: 600;
}
.nav-menu li a span { font-size: 1.05rem; }

/* ── 主内容 ── */
.main-content {
  max-width: 1100px;
  margin: 0 auto;
  padding: 28px 20px 80px;
  min-height: calc(100vh - 120px);
}

/* ── 底部 ── */
.app-footer {
  text-align: center;
  padding: 16px 20px;
  color: var(--text-muted);
  font-size: 0.82rem;
  border-top: 1px solid var(--border);
  display: flex;
  justify-content: space-between;
  max-width: 1100px;
  margin: 0 auto;
}

/* ── 页面标题 ── */
.page-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 24px;
  flex-wrap: wrap;
  gap: 12px;
}
.page-header h2 { font-size: 1.5rem; font-weight: 700; letter-spacing: -0.02em; }
.page-header .subtitle { color: var(--text-secondary); font-size: 0.9rem; }

/* ── 卡片 ── */
.card {
  background: var(--bg-card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 24px;
  margin-bottom: 16px;
  transition: all var(--transition);
  border: 1px solid var(--border);
}
.card:hover { box-shadow: var(--shadow-lg); }
.card-title {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 16px;
}
.card-title .badge {
  font-size: 0.78rem;
  padding: 3px 12px;
  border-radius: 20px;
  font-weight: 500;
  margin-left: 8px;
}
.badge-primary { background: var(--primary-light); color: var(--primary); }
.badge-success { background: var(--success-light); color: var(--success); }
.badge-danger { background: var(--danger-light); color: var(--danger); }
.badge-warning { background: var(--warning-light); color: var(--warning); }

/* ── 按钮 ── */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 10px 22px;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 0.92rem;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition);
  white-space: nowrap;
}
.btn:active { transform: scale(0.97); }
.btn-primary { background: var(--gradient-primary); color: #fff; box-shadow: 0 2px 8px rgba(74, 111, 165, 0.3); }
.btn-primary:hover { box-shadow: 0 4px 16px rgba(74, 111, 165, 0.4); transform: translateY(-1px); }
.btn-success { background: var(--gradient-success); color: #fff; }
.btn-danger { background: var(--gradient-danger); color: #fff; }
.btn-warning { background: var(--warning); color: #fff; }
.btn-outline {
  background: transparent;
  color: var(--text);
  border: 1.5px solid var(--border);
}
.btn-outline:hover { background: var(--bg-hover); border-color: var(--primary); color: var(--primary); }
.btn-sm { padding: 7px 14px; font-size: 0.82rem; }
.btn-lg { padding: 14px 32px; font-size: 1.05rem; border-radius: var(--radius-sm); }
.btn-block { width: 100%; }
.btn:disabled { opacity: 0.45; cursor: not-allowed; transform: none; }

.btn-group {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

/* ── 表单 ── */
.form-group { margin-bottom: 16px; }
.form-label {
  display: block;
  font-size: 0.88rem;
  font-weight: 500;
  margin-bottom: 6px;
  color: var(--text-secondary);
}
.form-input, .form-select, .form-textarea {
  width: 100%;
  padding: 11px 16px;
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 0.92rem;
  background: var(--bg-card);
  color: var(--text);
  transition: all var(--transition);
}
.form-input:focus, .form-select:focus, .form-textarea:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--primary-light);
}
.form-textarea { min-height: 100px; resize: vertical; }

/* ── 文件上传区域 ── */
.upload-zone {
  border: 2px dashed var(--border);
  border-radius: var(--radius);
  padding: 48px 20px;
  text-align: center;
  cursor: pointer;
  transition: all var(--transition);
  background: var(--bg-card);
}
.upload-zone:hover, .upload-zone.dragover {
  border-color: var(--primary);
  background: var(--primary-light);
}
.upload-zone .upload-icon { font-size: 3.5rem; margin-bottom: 12px; }
.upload-zone .upload-text { color: var(--text-secondary); font-size: 0.95rem; }
.upload-zone .upload-hint { color: var(--text-muted); font-size: 0.82rem; margin-top: 6px; }

/* ── 表格 ── */
.table-responsive { overflow-x: auto; border-radius: var(--radius-sm); }
table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.88rem;
}
th, td {
  padding: 12px 14px;
  text-align: left;
  border-bottom: 1px solid var(--border);
}
th {
  background: var(--bg-hover);
  font-weight: 600;
  color: var(--text-secondary);
  position: sticky;
  top: 0;
}
tr:last-child td { border-bottom: none; }
tr:hover td { background: var(--bg-hover); }

/* ── Toast 通知 ── */
.toast {
  position: fixed;
  bottom: 80px;
  left: 50%;
  transform: translateX(-50%) translateY(20px);
  background: var(--text);
  color: var(--bg);
  padding: 14px 28px;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  opacity: 0;
  transition: all 0.35s cubic-bezier(0.4, 0, 0.2, 1);
  z-index: 999;
  pointer-events: none;
  white-space: nowrap;
  max-width: 90vw;
  overflow: hidden;
  text-overflow: ellipsis;
  box-shadow: 0 4px 20px rgba(0,0,0,0.2);
}
.toast.show {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}
.toast.success { background: var(--success); color: #fff; }
.toast.error { background: var(--danger); color: #fff; }
.toast.warning { background: var(--warning); color: #fff; }

/* ── 首页仪表盘 ── */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 16px;
  margin-bottom: 24px;
}
.stat-card {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 24px 20px;
  text-align: center;
  box-shadow: var(--shadow);
  transition: all var(--transition);
  border: 1px solid var(--border);
}
.stat-card:hover { box-shadow: var(--shadow-lg); transform: translateY(-3px); }
.stat-card .stat-icon { font-size: 2rem; margin-bottom: 8px; }
.stat-card .stat-value {
  font-size: 1.8rem;
  font-weight: 700;
  color: var(--primary);
}
.stat-card .stat-label { color: var(--text-secondary); font-size: 0.85rem; margin-top: 4px; }

.quick-actions {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 14px;
}
.quick-action-card {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 24px 20px;
  box-shadow: var(--shadow);
  cursor: pointer;
  transition: all var(--transition);
  text-align: center;
  border: 1px solid var(--border);
}
.quick-action-card:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-3px);
  border-color: var(--primary);
}
.quick-action-card .qa-icon { font-size: 2.4rem; margin-bottom: 10px; }
.quick-action-card .qa-title { font-weight: 600; font-size: 1rem; margin-bottom: 4px; }
.quick-action-card .qa-desc { color: var(--text-secondary); font-size: 0.82rem; }

/* ── 题库卡片列表 ── */
.bank-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 16px;
}
.bank-card {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
  cursor: pointer;
  transition: all var(--transition);
  border: 1.5px solid transparent;
}
.bank-card:hover { box-shadow: var(--shadow-lg); border-color: var(--primary); }
.bank-card .bank-name { font-weight: 600; font-size: 1.05rem; margin-bottom: 8px; }
.bank-card .bank-meta { color: var(--text-secondary); font-size: 0.82rem; margin-bottom: 4px; }
.bank-card .bank-tags { display: flex; gap: 4px; flex-wrap: wrap; margin-top: 8px; }
.bank-card .bank-tags .tag {
  background: var(--primary-light);
  color: var(--primary);
  padding: 2px 12px;
  border-radius: 20px;
  font-size: 0.75rem;
}

/* ── 刷题界面 ── */
.study-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 20px;
  flex-wrap: wrap;
  gap: 12px;
}
.study-progress {
  display: flex;
  align-items: center;
  gap: 14px;
  flex-wrap: wrap;
}
.progress-bar {
  flex: 1;
  min-width: 120px;
  height: 10px;
  background: var(--bg-hover);
  border-radius: 5px;
  overflow: hidden;
}
.progress-bar .progress-fill {
  height: 100%;
  background: var(--gradient-primary);
  border-radius: 5px;
  transition: width 0.5s cubic-bezier(0.4, 0, 0.2, 1);
  box-shadow: 0 1px 4px rgba(74, 111, 165, 0.3);
}
.progress-text { font-size: 0.85rem; color: var(--text-secondary); white-space: nowrap; font-variant-numeric: tabular-nums; }

.question-card {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 32px;
  box-shadow: var(--shadow);
  margin-bottom: 20px;
  transition: background var(--transition);
  border: 1px solid var(--border);
}

.question-number {
  display: inline-block;
  background: var(--primary-light);
  color: var(--primary);
  padding: 3px 14px;
  border-radius: 20px;
  font-size: 0.82rem;
  font-weight: 600;
  margin-bottom: 14px;
}

.question-type-badge {
  display: inline-block;
  padding: 3px 12px;
  border-radius: 20px;
  font-size: 0.78rem;
  font-weight: 500;
  margin-left: 8px;
}
.type-single { background: #e3edf7; color: #4a6fa5; }
.type-multiple { background: #fef8e0; color: #e6a817; }
.type-judge { background: #e6f7ee; color: #2d8f5c; }

.question-text {
  font-size: 1.1rem;
  line-height: 1.7;
  margin-bottom: 24px;
  word-break: break-word;
}

/* 选项 */
.options-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.option-item {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 14px 18px;
  border: 2px solid var(--border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition);
  user-select: none;
}
.option-item:hover { border-color: var(--primary); background: var(--primary-light); }
.option-item .option-label {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: var(--bg-hover);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
  font-size: 0.85rem;
  flex-shrink: 0;
  transition: all var(--transition);
}
.option-item .option-text { flex: 1; line-height: 1.5; }
.option-item.selected {
  border-color: var(--primary);
  background: var(--primary-light);
}
.option-item.selected .option-label { background: var(--primary); color: #fff; }
.option-item.correct {
  border-color: var(--success);
  background: var(--success-light);
}
.option-item.correct .option-label { background: var(--success); color: #fff; }
.option-item.wrong {
  border-color: var(--danger);
  background: var(--danger-light);
}
.option-item.wrong .option-label { background: var(--danger); color: #fff; }

/* 判断题特殊选项 */
.option-item.judge-true, .option-item.judge-false {
  flex: 1;
  justify-content: center;
  font-size: 1.05rem;
  padding: 18px;
}

/* 解析 */
.explanation-box {
  margin-top: 16px;
  padding: 18px;
  border-radius: var(--radius-sm);
  display: none;
}
.explanation-box.show { display: block; }
.explanation-box.correct { background: var(--success-light); border-left: 4px solid var(--success); }
.explanation-box.wrong { background: var(--danger-light); border-left: 4px solid var(--danger); }
.explanation-box .exp-title { font-weight: 600; margin-bottom: 8px; font-size: 1rem; }
.explanation-box .exp-content { line-height: 1.6; }

/* 答案标注 */
.correct-answer-label {
  display: inline-block;
  margin-top: 8px;
  font-size: 0.88rem;
  color: var(--success);
  font-weight: 500;
}

/* 刷题底部操作栏 */
.study-actions {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
  margin-top: 20px;
}
.study-actions .btn-group { flex: 1; justify-content: center; }

/* 模式选择面板 */
.mode-panel {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 14px;
  margin-bottom: 20px;
}
.mode-btn {
  padding: 28px 20px;
  border: 2px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg-card);
  cursor: pointer;
  text-align: center;
  transition: all var(--transition);
}
.mode-btn:hover { border-color: var(--primary); background: var(--primary-light); transform: translateY(-3px); box-shadow: var(--shadow-lg); }
.mode-btn.active {
  border-color: var(--primary);
  background: var(--primary-light);
  box-shadow: 0 0 0 3px var(--primary-light);
}
.mode-btn .mode-icon { font-size: 2.2rem; margin-bottom: 8px; }
.mode-btn .mode-name { font-weight: 600; font-size: 1rem; }
.mode-btn .mode-desc { color: var(--text-secondary); font-size: 0.82rem; margin-top: 4px; }

/* 背题模式 */
.memorize-mode .options-list { display: none; }
.memorize-mode .explanation-box { display: block; }

/* 模拟考试 */
.exam-header {
  background: var(--danger-light);
  border: 1.5px solid var(--danger);
  border-radius: var(--radius-sm);
  padding: 14px 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 20px;
  animation: pulse-border 2s ease-in-out infinite;
}
@keyframes pulse-border {
  0%, 100% { border-color: var(--danger); }
  50% { border-color: transparent; }
}
.exam-timer {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--danger);
  font-variant-numeric: tabular-nums;
}
.exam-progress { color: var(--text-secondary); font-size: 0.9rem; }

/* 成绩报告 */
.report-card {
  text-align: center;
  padding: 48px 24px;
}
.report-card .score {
  font-size: 4rem;
  font-weight: 800;
  color: var(--primary);
  margin-bottom: 8px;
  line-height: 1;
}
.report-card .score-label { color: var(--text-secondary); font-size: 1.05rem; }
.report-details {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
  gap: 14px;
  margin-top: 28px;
}
.report-item {
  padding: 20px 16px;
  background: var(--bg-hover);
  border-radius: var(--radius-sm);
}
.report-item .ri-value { font-size: 1.5rem; font-weight: 700; }
.report-item .ri-label { color: var(--text-secondary); font-size: 0.85rem; margin-top: 4px; }

/* ── 错题本 & 收藏夹 ── */
.wrong-list, .fav-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.wrong-item, .fav-item {
  background: var(--bg-card);
  border-radius: var(--radius-sm);
  padding: 18px;
  border: 1px solid var(--border);
  transition: all var(--transition);
}
.wrong-item:hover, .fav-item:hover { border-color: var(--primary); }
.wrong-item .wi-question, .fav-item .fi-question { font-weight: 500; margin-bottom: 8px; }
.wrong-item .wi-meta, .fav-item .fi-meta { color: var(--text-secondary); font-size: 0.82rem; }
.wrong-item .wi-actions, .fav-item .fi-actions { margin-top: 10px; display: flex; gap: 8px; flex-wrap: wrap; }

/* ── 设置页面 ── */
.settings-section { margin-bottom: 24px; }
.settings-section h3 { font-size: 1rem; margin-bottom: 16px; }
.setting-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 0;
  border-bottom: 1px solid var(--border);
}
.setting-item:last-child { border-bottom: none; }
.setting-info .si-title { font-weight: 500; }
.setting-info .si-desc { color: var(--text-secondary); font-size: 0.82rem; margin-top: 2px; }

/* 开关 */
.toggle {
  position: relative;
  width: 50px;
  height: 28px;
  background: var(--border);
  border-radius: 14px;
  cursor: pointer;
  transition: all var(--transition);
  flex-shrink: 0;
}
.toggle.on { background: var(--primary); }
.toggle::after {
  content: '';
  position: absolute;
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: #fff;
  top: 2px;
  left: 2px;
  transition: all var(--transition);
  box-shadow: 0 1px 4px rgba(0,0,0,0.2);
  pointer-events: none;
}
.toggle.on::after { left: 24px; }

/* ── 首次使用引导 ── */
.onboarding-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.55);
  z-index: 9999;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
  backdrop-filter: blur(4px);
}
.onboarding-card {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 48px 36px;
  max-width: 480px;
  width: 100%;
  text-align: center;
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--border);
}
.onboarding-card .ob-icon { font-size: 4rem; margin-bottom: 16px; }
.onboarding-card h2 { font-size: 1.5rem; margin-bottom: 12px; }
.onboarding-card p { color: var(--text-secondary); line-height: 1.7; margin-bottom: 8px; }
.onboarding-card .btn { margin-top: 16px; }

/* ── 空状态 ── */
.empty-state {
  text-align: center;
  padding: 60px 20px;
  color: var(--text-muted);
}
.empty-state .empty-icon { font-size: 4rem; margin-bottom: 16px; }
.empty-state .empty-text { font-size: 1.1rem; margin-bottom: 8px; }
.empty-state .empty-hint { font-size: 0.88rem; }

/* ── 用户选择器 ── */
.user-selector-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.55);
  z-index: 9999;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
  backdrop-filter: blur(4px);
}
.user-selector-card {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 40px 32px;
  max-width: 400px;
  width: 100%;
  text-align: center;
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--border);
}
.user-selector-card h2 { font-size: 1.3rem; margin-bottom: 20px; }
.user-selector-card .user-btn {
  display: block;
  width: 100%;
  padding: 14px 20px;
  margin-bottom: 10px;
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg-card);
  cursor: pointer;
  font-size: 1rem;
  color: var(--text);
  text-align: center;
  transition: all var(--transition);
}
.user-selector-card .user-btn:hover {
  border-color: var(--primary);
  background: var(--primary-light);
}
.user-selector-card .new-user-input {
  width: 100%;
  padding: 12px 16px;
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 1rem;
  background: var(--bg-card);
  color: var(--text);
  margin-bottom: 10px;
}
.user-selector-card .new-user-input:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--primary-light);
}

/* ── 模式对话框 ── */
.mode-dialog-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.55);
  z-index: 9999;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
  backdrop-filter: blur(4px);
}
.mode-dialog-card {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 32px 28px;
  max-width: 520px;
  width: 100%;
  max-height: 90vh;
  overflow-y: auto;
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--border);
}
.mode-dialog-card h3 { font-size: 1.2rem; margin-bottom: 4px; text-align: center; }
.mode-dialog-card .dialog-subtitle { text-align: center; color: var(--text-secondary); font-size: 0.9rem; margin-bottom: 20px; }
.mode-dialog-card .type-section { margin: 16px 0 10px; font-weight: 500; color: var(--text-secondary); }

/* ── 用户选择器 ── */
.user-selector-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.6);
  z-index: 99999;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
  backdrop-filter: blur(4px);
}
.user-selector-card {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 40px 32px;
  max-width: 400px;
  width: 100%;
  text-align: center;
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--border);
}
.user-selector-card h2 { font-size: 1.3rem; margin-bottom: 8px; }
.user-selector-card p { color: var(--text-secondary); margin-bottom: 20px; }
.user-selector-card .user-btn {
  display: block;
  width: 100%;
  padding: 14px 20px;
  margin-bottom: 10px;
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg-card);
  cursor: pointer;
  font-size: 1rem;
  color: var(--text);
  text-align: center;
  transition: all var(--transition);
}
.user-selector-card .user-btn:hover {
  border-color: var(--primary);
  background: var(--primary-light);
}
.user-selector-card .new-user-input {
  width: 100%;
  padding: 12px 16px;
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 1rem;
  background: var(--bg-card);
  color: var(--text);
  margin-bottom: 10px;
}
.user-selector-card .new-user-input:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--primary-light);
}

/* ── 模式选项对话框 ── */
.mode-options-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.55);
  z-index: 9999;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
  backdrop-filter: blur(4px);
}
.mode-options-card {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 32px 28px;
  max-width: 420px;
  width: 100%;
  max-height: 88vh;
  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--border);
}
.mode-options-card h3 { font-size: 1.15rem; margin-bottom: 16px; text-align: center; }
.mode-options-card .form-label { text-align: left; }
.mode-options-card .opt-row {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 14px;
}
.mode-options-card .opt-row label {
  min-width: 80px;
  font-size: 0.9rem;
  color: var(--text-secondary);
}
.mode-options-card .opt-row input {
  flex: 1;
  padding: 10px 14px;
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  background: var(--bg-card);
  color: var(--text);
}
.mode-options-card .opt-row input:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--primary-light);
}
.mode-options-card .opt-actions {
  display: flex;
  gap: 10px;
  margin-top: 16px;
  justify-content: center;
}
.mode-options-card .opt-actions .btn { flex: 1; }
.mode-options-card .dialog-subtitle {
  color: var(--text-secondary);
  font-size: 0.88rem;
  margin-bottom: 16px;
  text-align: center;
}
.mode-options-card .type-section {
  font-size: 0.95rem;
  font-weight: 600;
  margin: 16px 0 8px;
  text-align: left;
}
.mode-options-card .mode-panel { margin-bottom: 0; }

/* ── 响应式 ── */
@media (max-width: 768px) {
  .nav-toggle { display: block; }
  .nav-menu {
    display: none;
    flex-direction: column;
    padding: 8px 20px 12px;
  }
  .nav-menu.open { display: flex; }
  .nav-menu li a { padding: 12px 14px; }

  .main-content { padding: 20px 14px 80px; }
  .page-header h2 { font-size: 1.25rem; }

  .stats-grid { grid-template-columns: repeat(2, 1fr); }
  .quick-actions { grid-template-columns: 1fr; }
  .bank-grid { grid-template-columns: 1fr; }
  .mode-panel { grid-template-columns: repeat(2, 1fr); }

  .question-card { padding: 24px 16px; }
  .question-text { font-size: 1rem; }
  .option-item { padding: 12px 14px; }

  .study-actions { flex-direction: column; }
  .study-actions .btn-group { width: 100%; flex-wrap: nowrap; }
  .study-actions .btn-group .btn { flex: 1; font-size: 0.8rem; padding: 8px 10px; }

  .settings-section { margin-bottom: 16px; }
  .setting-item { flex-direction: column; align-items: flex-start; gap: 8px; }

  .app-footer { flex-direction: column; gap: 4px; }
  .exam-header { flex-direction: column; gap: 8px; text-align: center; }

  /* 模式/设置对话框：手机端占满宽度、内可滚动 */
  .mode-options-overlay { padding: 12px; align-items: flex-start; overflow-y: auto; }
  .mode-options-card { padding: 24px 16px; max-height: 92vh; margin: auto; }
  .mode-options-card .mode-btn { padding: 18px 12px; }
  .mode-options-card .mode-btn .mode-icon { font-size: 1.8rem; }
  .mode-options-card .opt-row { flex-wrap: wrap; }
  .mode-options-card .opt-row label { min-width: 72px; }
}

@media (max-width: 480px) {
  .stats-grid { grid-template-columns: 1fr; }
  .mode-panel { grid-template-columns: 1fr; }
  .report-details { grid-template-columns: repeat(2, 1fr); }
  .btn-lg { padding: 12px 24px; font-size: 0.95rem; }
}

/* ── 动画 ── */
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}
.fade-in { animation: fadeIn 0.35s ease; }

@keyframes slideUp {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}
.slide-up { animation: slideUp 0.4s ease; }

/* ── 滚动条 ── */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--text-muted); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--text-secondary); }