/* ==================== 设计系统 ==================== */
:root {
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --primary-light: #eff6ff;
  --success: #16a34a;
  --success-light: #f0fdf4;
  --warning: #d97706;
  --warning-light: #fffbeb;
  --danger: #dc2626;
  --danger-light: #fef2f2;
  --gray-50: #f8fafc;
  --gray-100: #f1f5f9;
  --gray-200: #e2e8f0;
  --gray-300: #cbd5e1;
  --gray-400: #94a3b8;
  --gray-500: #64748b;
  --gray-600: #475569;
  --gray-700: #334155;
  --gray-800: #1e293b;
  --gray-900: #0f172a;
  --radius: 8px;
  --radius-lg: 12px;
  --shadow: 0 1px 3px rgba(15, 23, 42, 0.08);
  --shadow-lg: 0 8px 24px rgba(15, 23, 42, 0.12);
  --sidebar-w: 216px;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  font-size: 14px;
  line-height: 1.6;
  color: var(--gray-700);
  background: var(--gray-50);
  -webkit-font-smoothing: antialiased;
}

a { color: var(--primary); text-decoration: none; }
button, input, select, textarea { font-family: inherit; font-size: inherit; }

/* ==================== 登录页 ==================== */
.login-page {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, #1e3a8a 0%, #2563eb 50%, #3b82f6 100%);
  padding: 20px;
}
.login-box {
  width: 100%;
  max-width: 400px;
  background: #fff;
  border-radius: var(--radius-lg);
  padding: 40px;
  box-shadow: var(--shadow-lg);
}
.login-box h1 { font-size: 22px; color: var(--gray-900); margin-bottom: 6px; font-weight: 600; }
.login-box .sub { color: var(--gray-500); font-size: 13px; margin-bottom: 28px; }
.login-box .hint {
  margin-top: 20px;
  padding: 12px 14px;
  background: var(--gray-50);
  border-radius: var(--radius);
  font-size: 12px;
  color: var(--gray-600);
  line-height: 1.9;
}
.login-box .hint b { color: var(--gray-800); }

/* ==================== 后台布局 ==================== */
.layout { display: flex; min-height: 100vh; }

.sidebar {
  width: var(--sidebar-w);
  background: var(--gray-800);
  color: var(--gray-300);
  display: flex;
  flex-direction: column;
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  z-index: 20;
}
.sidebar .brand {
  padding: 18px 20px;
  font-size: 16px;
  font-weight: 600;
  color: #fff;
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
  display: flex;
  align-items: center;
  gap: 8px;
}
.sidebar .brand .dot {
  width: 8px; height: 8px; border-radius: 50%;
  background: #38bdf8;
}
.nav { flex: 1; overflow-y: auto; padding: 12px 0; }
.nav a {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 20px;
  color: var(--gray-400);
  font-size: 13px;
  transition: all 0.15s;
  border-left: 3px solid transparent;
}
.nav a:hover { color: #fff; background: rgba(255, 255, 255, 0.05); }
.nav a.active {
  color: #fff;
  background: rgba(37, 99, 235, 0.18);
  border-left-color: var(--primary);
}
.nav .nav-group {
  padding: 14px 20px 6px;
  font-size: 11px;
  color: var(--gray-500);
  letter-spacing: 0.5px;
}
.sidebar .user-box {
  padding: 14px 20px;
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  font-size: 12px;
}
.sidebar .user-box .name { color: #fff; font-size: 13px; margin-bottom: 2px; }
.sidebar .user-box .role { color: var(--gray-500); }
.sidebar .user-box .logout {
  margin-top: 8px;
  color: var(--gray-400);
  cursor: pointer;
  font-size: 12px;
}
.sidebar .user-box .logout:hover { color: #f87171; }

.main {
  flex: 1;
  margin-left: var(--sidebar-w);
  display: flex;
  flex-direction: column;
  min-width: 0;
}
.topbar {
  height: 56px;
  background: #fff;
  border-bottom: 1px solid var(--gray-200);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 24px;
  position: sticky;
  top: 0;
  z-index: 10;
}
.topbar h2 { font-size: 16px; font-weight: 600; color: var(--gray-900); }
.topbar .actions { display: flex; gap: 8px; align-items: center; }
.content { padding: 24px; flex: 1; }

/* ==================== 组件 ==================== */
.card {
  background: #fff;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow);
  padding: 20px;
  margin-bottom: 16px;
}
.card h3 {
  font-size: 15px;
  font-weight: 600;
  color: var(--gray-900);
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}
.card h3 .sub { font-size: 12px; font-weight: 400; color: var(--gray-500); }

.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 7px 14px;
  border: 1px solid var(--gray-300);
  background: #fff;
  border-radius: var(--radius);
  cursor: pointer;
  font-size: 13px;
  color: var(--gray-700);
  transition: all 0.15s;
  white-space: nowrap;
}
.btn:hover { border-color: var(--gray-400); background: var(--gray-50); }
.btn-primary { background: var(--primary); border-color: var(--primary); color: #fff; }
.btn-primary:hover { background: var(--primary-dark); border-color: var(--primary-dark); }
.btn-danger { background: #fff; border-color: #fca5a5; color: var(--danger); }
.btn-danger:hover { background: var(--danger-light); }
.btn-sm { padding: 4px 10px; font-size: 12px; }
.btn-lg { padding: 10px 20px; font-size: 14px; }
.btn:disabled { opacity: 0.5; cursor: not-allowed; }
.btn-block { width: 100%; justify-content: center; }

.form-group { margin-bottom: 16px; }
.form-group label {
  display: block;
  font-size: 13px;
  color: var(--gray-700);
  margin-bottom: 6px;
  font-weight: 500;
}
.form-group .tip { font-size: 12px; color: var(--gray-500); margin-top: 4px; font-weight: 400; }
input[type='text'], input[type='email'], input[type='password'], input[type='number'], input[type='datetime-local'], select, textarea {
  width: 100%;
  padding: 8px 12px;
  border: 1px solid var(--gray-300);
  border-radius: var(--radius);
  outline: none;
  transition: border-color 0.15s;
  background: #fff;
}
input:focus, select:focus, textarea:focus { border-color: var(--primary); }
textarea { resize: vertical; min-height: 80px; line-height: 1.6; }
.form-row { display: flex; gap: 12px; flex-wrap: wrap; }
.form-row > * { flex: 1; min-width: 160px; }

.table { width: 100%; border-collapse: collapse; font-size: 13px; }
.table th {
  text-align: left;
  padding: 10px 12px;
  background: var(--gray-50);
  color: var(--gray-600);
  font-weight: 500;
  border-bottom: 1px solid var(--gray-200);
  white-space: nowrap;
}
.table td { padding: 10px 12px; border-bottom: 1px solid var(--gray-100); vertical-align: middle; }
.table tr:hover td { background: var(--gray-50); }
.table .empty { text-align: center; padding: 40px; color: var(--gray-400); }

.tag {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 4px;
  font-size: 12px;
  line-height: 1.6;
  background: var(--gray-100);
  color: var(--gray-600);
}
.tag-blue { background: var(--primary-light); color: var(--primary); }
.tag-green { background: var(--success-light); color: var(--success); }
.tag-amber { background: var(--warning-light); color: var(--warning); }
.tag-red { background: var(--danger-light); color: var(--danger); }

.stat-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); gap: 12px; }
.stat-card {
  background: #fff;
  border-radius: var(--radius-lg);
  padding: 16px 18px;
  box-shadow: var(--shadow);
}
.stat-card .label { font-size: 12px; color: var(--gray-500); margin-bottom: 6px; }
.stat-card .value { font-size: 24px; font-weight: 600; color: var(--gray-900); line-height: 1.2; }
.stat-card .extra { font-size: 12px; color: var(--gray-400); margin-top: 4px; }

.toolbar {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  align-items: center;
  margin-bottom: 16px;
}
.toolbar input, .toolbar select { width: auto; min-width: 140px; }
.toolbar .spacer { flex: 1; }

.pagination {
  display: flex;
  gap: 6px;
  align-items: center;
  justify-content: flex-end;
  margin-top: 16px;
  font-size: 13px;
  color: var(--gray-500);
}

.empty-state {
  text-align: center;
  padding: 60px 20px;
  color: var(--gray-400);
}
.empty-state .icon { font-size: 40px; margin-bottom: 12px; opacity: 0.4; }

/* 模态框 */
.modal-mask {
  position: fixed;
  inset: 0;
  background: rgba(15, 23, 42, 0.45);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 100;
  padding: 20px;
}
.modal {
  background: #fff;
  border-radius: var(--radius-lg);
  width: 100%;
  max-width: 620px;
  max-height: 88vh;
  display: flex;
  flex-direction: column;
  box-shadow: var(--shadow-lg);
}
.modal.wide { max-width: 900px; }
.modal header {
  padding: 16px 20px;
  border-bottom: 1px solid var(--gray-200);
  font-size: 15px;
  font-weight: 600;
  color: var(--gray-900);
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.modal .body { padding: 20px; overflow-y: auto; flex: 1; }
.modal footer {
  padding: 14px 20px;
  border-top: 1px solid var(--gray-200);
  display: flex;
  justify-content: flex-end;
  gap: 8px;
}
.modal .close { cursor: pointer; color: var(--gray-400); font-size: 20px; line-height: 1; }
.modal .close:hover { color: var(--gray-700); }

/* Toast */
.toast-wrap { position: fixed; top: 20px; left: 50%; transform: translateX(-50%); z-index: 200; }
.toast {
  padding: 10px 18px;
  background: var(--gray-900);
  color: #fff;
  border-radius: var(--radius);
  margin-bottom: 8px;
  font-size: 13px;
  box-shadow: var(--shadow-lg);
  animation: toast-in 0.2s;
}
.toast.success { background: var(--success); }
.toast.error { background: var(--danger); }
@keyframes toast-in { from { opacity: 0; transform: translateY(-10px); } to { opacity: 1; transform: none; } }

/* 进度条 */
.progress { height: 8px; background: var(--gray-200); border-radius: 4px; overflow: hidden; }
.progress .bar { height: 100%; background: var(--primary); transition: width 0.3s; }
.progress .bar.green { background: var(--success); }
.progress .bar.amber { background: var(--warning); }

/* 图表条（纯 CSS，无需图表库） */
.bar-chart { display: flex; flex-direction: column; gap: 10px; }
.bar-row { display: flex; align-items: center; gap: 12px; font-size: 13px; }
.bar-row .bar-label { width: 100px; color: var(--gray-600); flex-shrink: 0; }
.bar-row .bar-track { flex: 1; height: 22px; background: var(--gray-100); border-radius: 4px; overflow: hidden; }
.bar-row .bar-fill { height: 100%; border-radius: 4px; display: flex; align-items: center; padding-left: 8px; color: #fff; font-size: 12px; }
.bar-row .bar-value { width: 80px; text-align: right; flex-shrink: 0; color: var(--gray-500); }

/* 富文本题干样式 */
.q-content { line-height: 1.8; }
.q-content img { max-width: 100%; }
.option-list { margin-top: 10px; }
.option-item {
  padding: 8px 12px;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  margin-bottom: 6px;
  cursor: pointer;
  transition: all 0.15s;
  display: flex;
  gap: 10px;
}
.option-item:hover { border-color: var(--primary); background: var(--primary-light); }
.option-item.selected { border-color: var(--primary); background: var(--primary-light); }
.option-item .key { font-weight: 600; color: var(--gray-700); flex-shrink: 0; }
.option-item.correct { border-color: var(--success); background: var(--success-light); }
.option-item.wrong { border-color: var(--danger); background: var(--danger-light); }
.option-item.disabled { cursor: default; }
.option-item.disabled:hover { border-color: var(--gray-200); background: #fff; }

.grid-2 { display: grid; grid-template-columns: repeat(auto-fit, minmax(320px, 1fr)); gap: 16px; }
.text-muted { color: var(--gray-500); font-size: 12px; }
.text-right { text-align: right; }
.mt-8 { margin-top: 8px; }
.mt-16 { margin-top: 16px; }
.mb-12 { margin-bottom: 12px; }
.flex { display: flex; gap: 8px; align-items: center; }
.wrap { flex-wrap: wrap; }
.nowrap { white-space: nowrap; }
.ellipsis { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; max-width: 320px; display: inline-block; vertical-align: bottom; }

/* ==================== 答题页 ==================== */
.exam-page { background: #fff; min-height: 100vh; }
.exam-header {
  position: sticky;
  top: 0;
  background: #fff;
  border-bottom: 1px solid var(--gray-200);
  padding: 12px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  z-index: 10;
  box-shadow: var(--shadow);
}
.exam-header .title { font-size: 16px; font-weight: 600; color: var(--gray-900); }
.timer {
  font-size: 20px;
  font-weight: 600;
  color: var(--primary);
  font-variant-numeric: tabular-nums;
}
.timer.warning { color: var(--warning); }
.timer.danger { color: var(--danger); }
.exam-body { display: flex; gap: 24px; padding: 24px; max-width: 1280px; margin: 0 auto; }
.exam-main { flex: 1; min-width: 0; }
.exam-side { width: 240px; flex-shrink: 0; }
.exam-side .card { position: sticky; top: 80px; }
.q-nav { display: grid; grid-template-columns: repeat(5, 1fr); gap: 6px; }
.q-nav-item {
  aspect-ratio: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--gray-300);
  border-radius: 6px;
  cursor: pointer;
  font-size: 13px;
  color: var(--gray-600);
  background: #fff;
}
.q-nav-item.answered { background: var(--primary); border-color: var(--primary); color: #fff; }
.q-nav-item.current { outline: 2px solid var(--primary); outline-offset: 1px; }
.q-nav-item.marked { background: var(--warning); border-color: var(--warning); color: #fff; }
.q-card { border: 1px solid var(--gray-200); border-radius: var(--radius-lg); padding: 20px; margin-bottom: 16px; background: #fff; }
.q-card .q-head { display: flex; gap: 10px; align-items: baseline; margin-bottom: 12px; }
.q-card .q-index { font-weight: 600; color: var(--gray-900); }
.q-card .q-score { font-size: 12px; color: var(--gray-500); }
.q-actions { display: flex; gap: 8px; justify-content: space-between; margin-top: 20px; }
.cheat-warn {
  position: fixed;
  top: 50%; left: 50%;
  transform: translate(-50%, -50%);
  background: rgba(220, 38, 38, 0.95);
  color: #fff;
  padding: 20px 32px;
  border-radius: var(--radius-lg);
  font-size: 16px;
  z-index: 300;
  box-shadow: var(--shadow-lg);
  text-align: center;
}
.cheat-warn .sub { font-size: 13px; opacity: 0.9; margin-top: 6px; }

/* ==================== 证书 ==================== */
.cert-wrap {
  background: linear-gradient(135deg, #f8fafc 0%, #eef2ff 100%);
  padding: 32px;
  border-radius: var(--radius-lg);
  text-align: center;
  border: 8px solid #cbd5e1;
}
.cert-wrap h2 { font-size: 28px; color: var(--gray-900); letter-spacing: 4px; margin-bottom: 8px; }
.cert-wrap .cert-name { font-size: 22px; color: var(--gray-800); margin: 24px 0; font-weight: 600; }
.cert-wrap .cert-desc { line-height: 2; color: var(--gray-600); margin-bottom: 20px; }
.cert-wrap .cert-footer {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  margin-top: 32px;
  padding-top: 20px;
  border-top: 1px dashed var(--gray-300);
}
.cert-wrap .cert-serial { font-family: monospace; color: var(--gray-500); font-size: 13px; }

@media (max-width: 900px) {
  .exam-body { flex-direction: column; }
  .exam-side { width: 100%; }
  .exam-side .card { position: static; }
  .sidebar { width: 60px; }
  .sidebar .brand span, .nav a span, .sidebar .user-box .detail { display: none; }
  .main { margin-left: 60px; }
}

/* ==================== 扩展组件 ==================== */
.mt-12 { margin-top: 12px; }

/* 进度条：兼容 .bar 与 .progress-bar 两种写法 */
.progress > .bar,
.progress > .progress-bar {
  height: 100%;
  border-radius: 4px;
  background: var(--primary);
  transition: width 0.3s;
  display: block;
}

/* 分隔线 */
.divider {
  height: 1px;
  background: var(--gray-200);
  margin: 16px 0;
  border: 0;
}

/* 复选行 */
label.checkbox {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 14px;
  color: var(--gray-700);
  cursor: pointer;
  user-select: none;
}
label.checkbox input { width: auto; margin: 0; }

/* 选项卡 */
.tabs {
  display: flex;
  gap: 4px;
  border-bottom: 1px solid var(--gray-200);
  margin-bottom: 4px;
}
.tab {
  padding: 8px 14px;
  border: 0;
  background: transparent;
  color: var(--gray-600);
  font-size: 14px;
  cursor: pointer;
  border-bottom: 2px solid transparent;
  border-radius: 0;
  display: flex;
  align-items: center;
  gap: 6px;
}
.tab:hover { color: var(--gray-900); }
.tab.active {
  color: var(--primary);
  border-bottom-color: var(--primary);
  font-weight: 600;
}

/* 列表卡片（错题、阅卷条目） */
.card-item {
  display: flex;
  align-items: flex-start;
  padding: 14px;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  margin-bottom: 10px;
  background: #fff;
}
.card-item.is-mastered { background: var(--gray-50); }

/* 作答内容框 */
.answer-box {
  background: var(--gray-50);
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  padding: 10px 12px;
  font-size: 14px;
  line-height: 1.75;
  white-space: pre-wrap;
  word-break: break-word;
  min-height: 44px;
}
.answer-box.ref { background: #f0f9ff; border-color: #bae6fd; color: var(--gray-700); }

/* AI 预评提示 */
.ai-hint {
  margin-top: 10px;
  padding: 10px 12px;
  background: linear-gradient(90deg, #eff6ff, #f5f3ff);
  border: 1px solid #bfdbfe;
  border-radius: var(--radius);
  font-size: 14px;
}

/* 证书列表 */
.cert-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 14px;
}
.cert-card {
  position: relative;
  padding: 16px;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-lg);
  background: linear-gradient(160deg, #f8fafc, #eef2ff);
  cursor: pointer;
  transition: transform 0.15s, box-shadow 0.15s;
}
.cert-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(15, 23, 42, 0.1);
}
.cert-badge {
  position: absolute;
  top: 12px;
  right: 12px;
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: var(--success);
  color: #fff;
  font-size: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
}
.cert-card .cert-title { font-weight: 600; font-size: 15px; padding-right: 32px; }
.cert-no { margin-top: 10px; font-size: 12px; color: var(--gray-500); }

/* 证书详情（弹窗内） */
.cert-wrap .cert-head { text-align: center; margin-bottom: 16px; }
.cert-wrap .cert-org { font-size: 13px; color: var(--gray-500); letter-spacing: 2px; }
.cert-wrap .cert-body { line-height: 2.1; color: var(--gray-700); }
.cert-wrap .cert-foot {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  margin-top: 28px;
  padding-top: 16px;
  border-top: 1px dashed var(--gray-300);
}
.cert-wrap .cert-qr {
  position: absolute;
  right: 32px;
  bottom: 32px;
  width: 96px;
}
.cert-wrap .cert-qr img { width: 96px; height: 96px; display: block; }

/* 证书容器定位（二维码绝对定位依赖） */
.cert-wrap { position: relative; }

/* ==================== 移动端适配（≤640px） ==================== */
/* Round 13 审计结论：375px 视口下全站表格以最小内容宽度（778~1091px）渲染且
   无任何滚动容器，操作列被裁剪不可达——学生连「开始考试」都点不到（td 拦截
   指针事件的实证见 scripts/e2e-mobile.js）。修复策略：容器允许横向滚动 +
   收紧内边距 + 触摸目标达标 + 表单可及名称。 */
@media (max-width: 640px) {
  .content {
    padding: 12px;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
  }
  .card {
    padding: 12px;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
  }
  .topbar { padding: 0 12px; }
  .topbar h2 { font-size: 15px; }
  .table { font-size: 12px; }
  .table th { padding: 8px 10px; }
  .table td { padding: 8px 10px; }
  /* 触摸目标 ≥44px（WCAG 2.5.5 / iOS HIG） */
  .option-item { min-height: 44px; }
  .btn-sm { min-height: 36px; padding: 8px 12px; }
  /* 弹窗在小屏不超出视口 */
  .modal { max-width: calc(100vw - 32px); }
}