/* ================================================
   LearnHub - BBS Forum with Online Courses
   自定义样式表 (配合 Bootstrap 5)
   ================================================ */

/* ===== CSS 变量 ===== */
:root {
  --brand-primary: #0056d2;
  --brand-accent: #00419a;
  --bg-page: #f8f9fb;
  --bg-card: #ffffff;
  --bg-input: #f3f5f9;
  --bg-muted: #f0f3f8;
  --bg-secondary: #e8f0fe;
  --text-primary: #1f1f1f;
  --text-primary-title: #0056D2;
  --text-muted: #636363;
  --border-color: rgba(0, 0, 0, 0.1);
  --danger: #c9241c;
  --radius: 0.625rem;
}

/* ===== 全局样式 ===== */
* {
  box-sizing: border-box;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  background-color: var(--bg-page);
  color: var(--text-primary);
  font-size: 16px;
  line-height: 1.5;
}

/* Source Serif 4 用于标题 */
h1, h2, h3, h4,
.serif-title {
  font-family: 'Source Serif 4', Georgia, serif;
}

/* ===== 导航栏 ===== */
.navbar-learnhub {
  background-color: var(--bg-card);
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 1030;
}

.navbar-learnhub .nav-link {
  /*color: var(--text-muted);*/
  font-size: 0.875rem;
  font-weight: 500;
  padding: 0.375rem 0.75rem;
  border-radius: 0.5rem;
  transition: all 0.15s;
}

.navbar-learnhub .nav-link:hover {
  color: var(--text-primary);
  background-color: var(--bg-muted);
}

.navbar-learnhub .nav-link.active {
  color: var(--brand-primary);
  background-color: var(--bg-secondary);
}

.navbar-brand-logo {
  width: 28px;
  height: 28px;
  background-color: var(--brand-primary);
  border-radius: 4px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
}

.navbar-brand-text {
  font-family: 'Source Serif 4', Georgia, serif;
  font-weight: 600;
  font-size: 2rem;
  color: var(--text-primary-title);
}

/* 通知红点 */
.notification-dot {
  position: absolute;
  top: 0;
  right: -2px;
  width: 8px;
  height: 8px;
  background-color: var(--danger);
  border-radius: 50%;
}

/* 用户头像 */
.avatar-sm { width: 32px; height: 32px; }
.avatar-md { width: 40px; height: 40px; }
.avatar-lg { width: 48px; height: 48px; }
.avatar { border-radius: 50%; object-fit: cover; }

/* ===== 登录页 ===== */
.login-container {
  min-height: 100vh;
}

.login-left {
  background-color: var(--brand-primary);
  background-image:
    radial-gradient(circle at 20% 50%, rgba(255,255,255,0.12) 1px, transparent 1px),
    radial-gradient(circle at 80% 20%, rgba(255,255,255,0.12) 1px, transparent 1px);
  background-size: 60px 60px;
}

.login-left-content {
  position: relative;
  z-index: 1;
}

.login-left h1 {
  color: #fff;
  font-size: 2.75rem;
  font-weight: 700;
}

.login-left p {
  color: rgba(255, 255, 255, 0.85);
}

.stat-item .stat-value {
  color: #fff;
  font-size: 1.5rem;
  font-weight: 700;
}

.stat-item .stat-label {
  color: rgba(255, 255, 255, 0.65);
  font-size: 0.875rem;
}

.login-right {
  display: flex;
  align-items: center;
  justify-content: center;
}

.login-form-box {
  width: 100%;
  max-width: 420px;
}

/* 登录 Tab */
.nav-login-tabs .nav-link {
  color: var(--text-muted);
  border: none;
  border-bottom: 2px solid transparent;
  font-size: 0.875rem;
  font-weight: 500;
  padding: 0.75rem 0;
  margin-right: 1.5rem;
}

.nav-login-tabs .nav-link.active {
  color: var(--brand-primary);
  border-bottom-color: var(--brand-primary);
  background: none;
}

/* 表单样式 */
.form-control-custom {
  background-color: var(--bg-input);
  border: 1px solid var(--border-color);
  border-radius: 0.5rem;
  padding: 0.75rem 1rem;
  font-size: 0.875rem;
  color: var(--text-primary);
  transition: all 0.15s;
}

.form-control-custom:focus {
  border-color: var(--brand-primary);
  box-shadow: 0 0 0 3px rgba(0, 86, 210, 0.12);
  outline: none;
  background-color: var(--bg-input);
}

.form-control-custom::placeholder {
  color: var(--text-muted);
}

.btn-brand {
  background-color: var(--brand-primary);
  color: #fff;
  border: none;
  padding: 0.75rem;
  font-weight: 600;
  border-radius: 0.5rem;
  transition: background-color 0.15s;
}

.btn-brand:hover {
  background-color: var(--brand-accent);
  color: #fff;
}

/* ===== 卡片 ===== */
.card-custom {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
}

.card-custom-hover {
  transition: all 0.2s;
  cursor: pointer;
}

.card-custom-hover:hover {
  border-color: rgba(0, 86, 210, 0.3);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.06);
}

/* ===== 统计卡片 ===== */
.stat-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 1.25rem;
}

.stat-card .stat-icon {
  margin-bottom: 0.75rem;
}

.stat-card .stat-value {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
}

.stat-card .stat-label {
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: 0.25rem;
}

/* ===== 课程卡片 ===== */
.course-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  overflow: hidden;
  transition: all 0.2s;
  cursor: pointer;
}

.course-card:hover {
  border-color: rgba(0, 86, 210, 0.3);
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.08);
}

.course-card .course-img {
  width: 100%;
  height: 176px;
  object-fit: cover;
  transition: opacity 0.15s;
}

.course-card:hover .course-img {
  opacity: 0.9;
}

.course-card .bookmark-btn {
  position: absolute;
  top: 0.75rem;
  right: 0.75rem;
  width: 32px;
  height: 32px;
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(4px);
  border-radius: 50%;
  border: none;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  box-shadow: 0 2px 6px rgba(0,0,0,0.08);
  transition: background-color 0.15s;
}

.course-card .bookmark-btn:hover {
  background: #fff;
}

.course-card .enrolled-badge {
  position: absolute;
  top: 0.75rem;
  left: 0.75rem;
  background-color: #22c55e;
  color: #fff;
  font-size: 0.75rem;
  font-weight: 500;
  padding: 0.25rem 0.5rem;
  border-radius: 0.375rem;
}

.course-card .course-info {
  padding: 1rem;
}

.course-card .provider {
  font-size: 0.75rem;
  color: var(--text-muted);
  font-weight: 500;
}

.course-card .title {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-primary);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

/* ===== 进度条 ===== */
.progress-custom {
  height: 6px;
  background-color: var(--bg-muted);
  border-radius: 999px;
  overflow: hidden;
}

.progress-custom .progress-bar-custom {
  height: 100%;
  background-color: var(--brand-primary);
  border-radius: 999px;
  transition: width 0.3s;
}

.progress-custom-sm {
  height: 4px;
}

/* ===== 继续学习卡片 ===== */
.continue-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  overflow: hidden;
  display: flex;
  cursor: pointer;
  transition: all 0.2s;
}

.continue-card:hover {
  border-color: rgba(0, 86, 210, 0.3);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.06);
}

.continue-card .continue-img {
  width: 128px;
  object-fit: cover;
}

/* ===== 论坛帖子列表 ===== */
.thread-item {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 1.25rem;
  cursor: pointer;
  transition: all 0.2s;
}

.thread-item:hover {
  border-color: rgba(0, 86, 210, 0.3);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.04);
}

.thread-title {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-primary);
}

/* ===== 论坛标签 ===== */
.tag-pill {
  font-size: 0.75rem;
  background-color: var(--bg-muted);
  color: var(--text-muted);
  padding: 0.25rem 0.5rem;
  border-radius: 0.375rem;
}

.tag-pill-active {
  background-color: var(--brand-primary);
  color: #fff;
}

.pinned-badge {
  font-size: 0.75rem;
  background-color: #fff7ed;
  color: #f97316;
  border: 1px solid #fed7aa;
  padding: 0.25rem 0.5rem;
  border-radius: 0.375rem;
  font-weight: 500;
}

/* ===== 课程详情页 ===== */
.course-hero {
  background-color: var(--text-primary);
  color: #fff;
}

.course-hero .btn-back {
  color: #93c5fd;
  font-size: 0.875rem;
}

.course-hero .btn-back:hover {
  color: #fff;
}

.level-badge {
  font-size: 0.75rem;
  background-color: #2563eb;
  color: #fff;
  padding: 0.25rem 0.75rem;
  border-radius: 0.375rem;
  font-weight: 500;
}

.cert-badge {
  font-size: 0.75rem;
  border: 1px solid #facc15;
  color: #facc15;
  padding: 0.25rem 0.75rem;
  border-radius: 0.375rem;
  font-weight: 500;
}

.course-detail-card {
  background: #fff;
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: 0 4px 24px rgba(0, 0, 0, 0.15);
}

.course-detail-card img {
  width: 100%;
  height: 176px;
  object-fit: cover;
}

/* 大纲项 */
.syllabus-item {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 0.5rem;
  padding: 1.25rem;
  transition: all 0.2s;
}

.syllabus-item:not(.locked) {
  cursor: pointer;
}

.syllabus-item:not(.locked):hover {
  border-color: rgba(0, 86, 210, 0.3);
}

.syllabus-item.locked {
  opacity: 0.55;
}

/* ===== 帖子详情页 ===== */
.post-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 2rem;
}

.reply-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 1.5rem;
}

.instructor-badge {
  font-size: 0.75rem;
  background-color: var(--bg-secondary);
  color: var(--brand-primary);
  padding: 0.125rem 0.5rem;
  border-radius: 999px;
  font-weight: 500;
}

/* ===== 分类按钮组 ===== */
.cat-btn {
  font-size: 0.875rem;
  font-weight: 500;
  padding: 0.375rem 1rem;
  border-radius: 999px;
  border: 1px solid var(--border-color);
  background: var(--bg-card);
  color: var(--text-primary);
  cursor: pointer;
  transition: all 0.15s;
}

.cat-btn:hover {
  border-color: rgba(0, 86, 210, 0.4);
}

.cat-btn.active {
  background-color: var(--brand-primary);
  color: #fff;
  border-color: var(--brand-primary);
}

/* ===== 筛选标签 ===== */
.filter-tag {
  font-size: 0.75rem;
  font-weight: 500;
  padding: 0.375rem 0.75rem;
  border-radius: 999px;
  border: 1px solid var(--border-color);
  background: var(--bg-card);
  color: var(--text-primary);
  cursor: pointer;
  transition: all 0.15s;
}

.filter-tag:hover {
  border-color: rgba(0, 86, 210, 0.4);
}

.filter-tag.active {
  background-color: var(--brand-primary);
  color: #fff;
  border-color: var(--brand-primary);
}

/* ===== 弹窗 ===== */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.5);
  z-index: 1055;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1rem;
}

.modal-dialog-custom {
  background: var(--bg-card);
  border-radius: 1rem;
  width: 100%;
  max-width: 520px;
  box-shadow: 0 12px 48px rgba(0, 0, 0, 0.2);
}

/* ===== 工具类 ===== */
.text-muted-custom { color: var(--text-muted) !important; }
.text-brand { color: var(--brand-primary) !important; }
.bg-page { background-color: var(--bg-page) !important; }
.bg-input { background-color: var(--bg-input) !important; }
.bg-muted { background-color: var(--bg-muted) !important; }
.bg-secondary-custom { background-color: var(--bg-secondary) !important; }
.border-custom { border-color: var(--border-color) !important; }
.rounded-custom { border-radius: var(--radius) !important; }
.text-price-free { color: #16a34a !important; }

/* line-clamp */
.line-clamp-2 {
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

/* ===== 响应式 ===== */
@media (max-width: 991.98px) {
  .login-left {
    display: none !important;
  }
}

/* ===== 星星评分 ===== */
.star-rating {
  color: #eab308;
  fill: #eab308;
}

/* ===== 页脚间距 ===== */
.page-content {
  padding-bottom: 2rem;
}

/* ===== select 样式 ===== */
select.form-control-custom {
  appearance: auto;
}

/* 密码切换按钮 */
.toggle-password {
  position: absolute;
  right: 0.75rem;
  top: 50%;
  transform: translateY(-50%);
  border: none;
  background: none;
  color: var(--text-muted);
  cursor: pointer;
  padding: 0;
}

.toggle-password:hover {
  color: var(--text-primary);
}

/* ===== 页脚 ===== */
.learnhub-footer {
  background-color: #fff;
  border-top: 1px solid var(--border-color);
  margin-top: 2rem;
}

.footer-title {
  font-family: 'Source Serif 4', Georgia, serif;
  font-size: 0.875rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.75rem;
}

.footer-links {
  list-style: none;
  padding: 0;
  margin: 0;
}

.footer-links li {
  margin-bottom: 0.5rem;
}

.footer-links a {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.8125rem;
  transition: color 0.15s;
}

.footer-links a:hover {
  color: var(--brand-primary);
}

.footer-social-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background-color: var(--bg-muted);
  color: var(--text-muted);
  text-decoration: none;
  transition: all 0.15s;
}

.footer-social-btn:hover {
  background-color: var(--brand-primary);
  color: #fff;
}

.footer-subscribe {
  display: flex;
  gap: 0.5rem;
}

.footer-subscribe .form-control-custom {
  flex: 1;
  font-size: 0.8125rem;
}

.footer-subscribe .btn-brand {
  font-size: 0.8125rem;
  padding: 0.5rem 1rem;
  white-space: nowrap;
}

.footer-help-link {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.8125rem;
  transition: color 0.15s;
}

.footer-help-link:hover {
  color: var(--brand-primary);
}

.footer-bottom {
  margin-top: 2.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border-color);
}

/* ===== Dashboard: 本周学习目标 ===== */
.goal-widget {
  background: linear-gradient(135deg, #0056d2 0%, #00419a 100%);
  border-radius: var(--radius);
  padding: 1.5rem;
  color: #fff;
  display: flex;
  align-items: center;
  gap: 1.5rem;
}

.goal-ring {
  position: relative;
  width: 88px;
  height: 88px;
  flex-shrink: 0;
}

.goal-ring svg {
  transform: rotate(-90deg);
}

.goal-ring .ring-text {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  text-align: center;
}

.goal-ring .ring-value {
  font-size: 1.25rem;
  font-weight: 700;
  line-height: 1;
}

.goal-ring .ring-unit {
  font-size: 0.625rem;
  color: rgba(255,255,255,0.7);
}

/* ===== Dashboard: 每日学习柱状图 ===== */
.activity-chart {
  display: flex;
  align-items: flex-end;
  gap: 0.5rem;
  height: 120px;
  padding-top: 0.5rem;
}

.activity-bar-group {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.375rem;
  height: 100%;
  justify-content: flex-end;
}

.activity-bar {
  width: 100%;
  max-width: 28px;
  border-radius: 4px 4px 0 0;
  background: linear-gradient(180deg, #0056d2 0%, #4a90e2 100%);
  min-height: 4px;
  transition: opacity 0.15s;
  position: relative;
  cursor: pointer;
}

.activity-bar:hover {
  opacity: 0.75;
}

.activity-bar.today {
  background: linear-gradient(180deg, #f97316 0%, #fbbf24 100%);
}

.activity-bar-label {
  font-size: 0.6875rem;
  color: var(--text-muted);
}

.activity-bar-value {
  font-size: 0.6875rem;
  color: var(--text-muted);
  position: absolute;
  top: -1.125rem;
  left: 50%;
  transform: translateX(-50%);
  white-space: nowrap;
  opacity: 0;
  transition: opacity 0.15s;
}

.activity-bar:hover .activity-bar-value {
  opacity: 1;
}

/* ===== Dashboard: 截止日期提醒 ===== */
.deadline-item {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.75rem 0;
  border-bottom: 1px solid var(--border-color);
}

.deadline-item:last-child {
  border-bottom: none;
}

.deadline-date {
  width: 44px;
  height: 44px;
  border-radius: 8px;
  background-color: var(--bg-muted);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.deadline-date .day {
  font-size: 1rem;
  font-weight: 700;
  line-height: 1;
  color: var(--text-primary);
}

.deadline-date .month {
  font-size: 0.625rem;
  color: var(--text-muted);
  line-height: 1;
}

.deadline-date.urgent {
  background-color: #fef2f2;
}

.deadline-date.urgent .day {
  color: var(--danger);
}

.deadline-date.urgent .month {
  color: var(--danger);
}

/* ===== Dashboard: 成就徽章 ===== */
.badge-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  text-align: center;
}

.badge-icon {
  width: 56px;
  height: 56px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
}

.badge-gold { background: linear-gradient(135deg, #fbbf24, #f59e0b); }
.badge-blue { background: linear-gradient(135deg, #3b82f6, #2563eb); }
.badge-green { background: linear-gradient(135deg, #34d399, #10b981); }
.badge-purple { background: linear-gradient(135deg, #a78bfa, #8b5cf6); }

.badge-name {
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--text-primary);
}

.badge-desc {
  font-size: 0.6875rem;
  color: var(--text-muted);
}

/* ===== Dashboard: 推荐课程小卡片 ===== */
.recommend-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  overflow: hidden;
  transition: all 0.2s;
  cursor: pointer;
}

.recommend-card:hover {
  border-color: rgba(0, 86, 210, 0.3);
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.08);
}

.recommend-card img {
  width: 100%;
  height: 120px;
  object-fit: cover;
}

.recommend-card .recommend-info {
  padding: 0.75rem;
}

/* ===== Dashboard: 快捷操作 ===== */
.quick-action {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.875rem 1rem;
  border-radius: 0.5rem;
  border: 1px solid var(--border-color);
  background: var(--bg-card);
  cursor: pointer;
  transition: all 0.15s;
  text-decoration: none;
  color: var(--text-primary);
}

.quick-action:hover {
  border-color: rgba(0, 86, 210, 0.3);
  background-color: var(--bg-muted);
  color: var(--text-primary);
}

.quick-action-icon {
  width: 36px;
  height: 36px;
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

/* ===== 视频播放页 ===== */
.video-player-wrapper {
  position: relative;
  background: #000;
  border-radius: var(--radius);
  overflow: hidden;
  aspect-ratio: 16 / 9;
}

.video-player-wrapper video {
  width: 100%;
  height: 100%;
  outline: none;
}

.video-info-section {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 1.5rem;
}

.video-meta-item {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.8125rem;
  color: var(--text-muted);
}

.playlist-item {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.75rem 1rem;
  border-radius: 0.5rem;
  cursor: pointer;
  transition: all 0.15s;
  border: 1px solid transparent;
}

.playlist-item:hover {
  background-color: var(--bg-muted);
}

.playlist-item.active {
  background-color: var(--bg-secondary);
  border-color: rgba(0, 86, 210, 0.3);
}

.playlist-item .playlist-num {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--bg-muted);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-muted);
  flex-shrink: 0;
}

.playlist-item.active .playlist-num,
.playlist-item.completed .playlist-num {
  background: var(--brand-primary);
  color: #fff;
}

.playlist-item .playlist-thumb {
  width: 88px;
  height: 50px;
  border-radius: 4px;
  object-fit: cover;
  flex-shrink: 0;
}

.playlist-item .playlist-duration {
  font-size: 0.6875rem;
  color: var(--text-muted);
  margin-top: 0.125rem;
}

.video-actions-bar {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.video-action-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.375rem;
  padding: 0.5rem 0.875rem;
  border-radius: 0.5rem;
  font-size: 0.8125rem;
  font-weight: 500;
  border: 1px solid var(--border-color);
  background: var(--bg-card);
  color: var(--text-primary);
  cursor: pointer;
  transition: all 0.15s;
}

.video-action-btn:hover {
  background: var(--bg-muted);
}

.video-action-btn.liked {
  color: var(--brand-primary);
  border-color: rgba(0, 86, 210, 0.3);
  background: var(--bg-secondary);
}

.video-progress-overlay {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: rgba(255,255,255,0.2);
  cursor: pointer;
}

.video-progress-overlay .video-progress-filled {
  height: 100%;
  background: var(--brand-primary);
  border-radius: 0 2px 2px 0;
}

.video-controls-overlay {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  background: linear-gradient(transparent, rgba(0,0,0,0.8));
  padding: 2rem 1rem 0.75rem;
  opacity: 0;
  transition: opacity 0.2s;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.video-player-wrapper:hover .video-controls-overlay {
  opacity: 1;
}

.video-ctrl-btn {
  background: none;
  border: none;
  color: #fff;
  cursor: pointer;
  padding: 0.25rem;
  display: flex;
  align-items: center;
  opacity: 0.85;
  transition: opacity 0.15s;
}

.video-ctrl-btn:hover {
  opacity: 1;
}

.video-time {
  color: #fff;
  font-size: 0.75rem;
  opacity: 0.8;
}

/* ================================================
   Home 首页 — Coursera 风格
   ================================================ */

/* ===== Hero 区域 ===== */
.min-vh-85 {
  min-height: 85vh;
}

.home-hero {
  background: linear-gradient(170deg, #f0f4ff 0%, #f8f9fb 40%, #fff 100%);
  position: relative;
  overflow: hidden;
}

.home-hero::before {
  content: '';
  position: absolute;
  top: -200px;
  right: -200px;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(0,86,210,0.06) 0%, transparent 70%);
  border-radius: 50%;
}

.home-hero::after {
  content: '';
  position: absolute;
  bottom: -150px;
  left: -100px;
  width: 400px;
  height: 400px;
  background: radial-gradient(circle, rgba(0,86,210,0.04) 0%, transparent 70%);
  border-radius: 50%;
}

.home-hero-title {
  font-family: 'Source Serif 4', Georgia, serif;
  font-size: 3rem;
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.15;
  letter-spacing: -0.02em;
}

.home-hero-sub {
  font-size: 1.125rem;
  color: var(--text-muted);
  max-width: 520px;
  line-height: 1.6;
}

.btn-home-primary {
  background-color: var(--brand-primary);
  color: #fff;
  border: none;
  padding: 0.75rem 1.75rem;
  font-weight: 600;
  border-radius: 0.5rem;
  font-size: 0.9375rem;
  transition: all 0.2s;
}

.btn-home-primary:hover {
  background-color: var(--brand-accent);
  color: #fff;
  transform: translateY(-1px);
  box-shadow: 0 4px 16px rgba(0,86,210,0.3);
}

.btn-home-outline {
  border: 2px solid var(--text-primary);
  color: var(--text-primary);
  padding: 0.75rem 1.75rem;
  font-weight: 600;
  border-radius: 0.5rem;
  font-size: 0.9375rem;
  transition: all 0.2s;
}

.btn-home-outline:hover {
  background-color: var(--text-primary);
  color: #fff;
  transform: translateY(-1px);
}

.home-hero-stat {
  text-align: center;
}

.home-hero-stat-value {
  display: block;
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.2;
}

.home-hero-stat-label {
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* Hero 视觉区域 */
.home-hero-visual {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
}

.home-hero-img {
  width: 100%;
  max-width: 560px;
  border-radius: 1rem;
}

.home-hero-float-card {
  position: absolute;
  background: #fff;
  border-radius: 0.75rem;
  padding: 0.75rem 1rem;
  box-shadow: 0 8px 32px rgba(0,0,0,0.1);
  border: 1px solid var(--border-color);
}

.home-hero-float-1 {
  top: 10%;
  left: 0;
}

.home-hero-float-2 {
  bottom: 15%;
  right: 5%;
}

/* ===== 通用区块 ===== */
.home-section {
  position: relative;
}

.home-section-title {
  font-family: 'Source Serif 4', Georgia, serif;
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.01em;
}

/* ===== 合作伙伴 Logo ===== */
.partner-logo-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  padding: 1rem 0.5rem;
  transition: transform 0.2s;
}

.partner-logo-card:hover {
  transform: translateY(-2px);
}

.partner-icon {
  width: 48px;
  height: 48px;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-size: 1.25rem;
  font-weight: 700;
  font-family: 'Source Serif 4', Georgia, serif;
}

.partner-name {
  font-size: 0.75rem;
  color: var(--text-muted);
  font-weight: 500;
  text-align: center;
}

.partner-cta-link {
  color: var(--brand-primary);
  text-decoration: none;
  font-size: 0.875rem;
  font-weight: 500;
  padding: 0.5rem 1rem;
  border-radius: 0.5rem;
  transition: background-color 0.15s;
}

.partner-cta-link:hover {
  background-color: var(--bg-secondary);
  color: var(--brand-accent);
}

/* ===== 热门课程标签页 ===== */
.home-tabs-nav {
  border-bottom: 2px solid var(--border-color);
  gap: 0.25rem;
}

.home-tabs-nav .nav-link {
  border: none;
  color: var(--text-muted);
  font-size: 0.9375rem;
  font-weight: 500;
  padding: 0.625rem 1.25rem;
  border-bottom: 2px solid transparent;
  margin-bottom: -2px;
  background: none;
  border-radius: 0;
  transition: all 0.15s;
}

.home-tabs-nav .nav-link:hover {
  color: var(--text-primary);
}

.home-tabs-nav .nav-link.active {
  color: var(--brand-primary);
  border-bottom-color: var(--brand-primary);
  background: none;
}

/* 课程卡片 (Home 专用) */
.home-course-card {
  background: #fff;
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  overflow: hidden;
  transition: all 0.2s;
}

.home-course-card:hover {
  border-color: rgba(0,86,210,0.3);
  box-shadow: 0 4px 20px rgba(0,0,0,0.1);
}

.home-course-img-wrap {
  position: relative;
  overflow: hidden;
}

.home-course-img-wrap img {
  width: 100%;
  height: 180px;
  object-fit: cover;
  display: block;
}

.home-course-badge {
  position: absolute;
  top: 0.75rem;
  left: 0.75rem;
  background: #16a34a;
  color: #fff;
  font-size: 0.6875rem;
  font-weight: 600;
  padding: 0.25rem 0.625rem;
  border-radius: 0.375rem;
  letter-spacing: 0.01em;
}

.home-course-body {
  padding: 1rem;
}

.home-course-provider {
  font-size: 0.6875rem;
  color: var(--text-muted);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.02em;
  margin-bottom: 0.25rem;
}

.home-course-title {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-primary);
  line-height: 1.4;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

/* ===== 分类卡片 ===== */
.category-card {
  display: flex;
  align-items: center;
  gap: 0.875rem;
  padding: 1rem 1.25rem;
  background: #fff;
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  transition: all 0.2s;
}

.category-card:hover {
  border-color: rgba(0,86,210,0.3);
  box-shadow: 0 4px 16px rgba(0,0,0,0.06);
  transform: translateY(-2px);
}

.category-icon {
  width: 44px;
  height: 44px;
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.category-name {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-primary);
}

/* ===== 促销横幅 ===== */
.promo-banner {
  border-radius: 1rem;
  min-height: 200px;
}

.promo-badge {
  display: inline-block;
  background: rgba(255,255,255,0.2);
  color: #fff;
  font-size: 0.75rem;
  font-weight: 600;
  padding: 0.25rem 0.75rem;
  border-radius: 999px;
}

/* ===== 目标卡片 ===== */
.goal-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  padding: 2rem 1.25rem;
  background: #fff;
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  transition: all 0.2s;
  height: 100%;
}

.goal-card:hover {
  border-color: rgba(0,86,210,0.3);
  box-shadow: 0 8px 24px rgba(0,0,0,0.08);
  transform: translateY(-3px);
}

.goal-card-icon {
  width: 60px;
  height: 60px;
  border-radius: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 1rem;
}

.goal-card-title {
  font-family: 'Source Serif 4', Georgia, serif;
  font-size: 1.0625rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.goal-card-desc {
  font-size: 0.8125rem;
  color: var(--text-muted);
  line-height: 1.5;
  margin-bottom: 0;
}

/* ===== 职业卡片 ===== */
.career-card {
  background: #fff;
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 1.5rem;
  transition: all 0.2s;
  height: 100%;
  display: flex;
  flex-direction: column;
}

.career-card:hover {
  border-color: rgba(0,86,210,0.3);
  box-shadow: 0 4px 20px rgba(0,0,0,0.08);
  transform: translateY(-2px);
}

.career-card-icon {
  width: 44px;
  height: 44px;
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 1rem;
}

.career-card-title {
  font-family: 'Source Serif 4', Georgia, serif;
  font-size: 1.0625rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.375rem;
}

.career-card-desc {
  font-size: 0.8125rem;
  color: var(--text-muted);
  line-height: 1.5;
  margin-bottom: 1rem;
  flex-grow: 1;
}

.career-card-stats {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-top: 0.75rem;
  border-top: 1px solid var(--border-color);
  gap: 0.5rem;
  flex-wrap: wrap;
}

.career-salary {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--brand-primary);
}

.career-jobs {
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* ===== 用户见证 ===== */
.testimonial-card {
  background: #fff;
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 1.5rem;
  height: 100%;
  display: flex;
  flex-direction: column;
  transition: all 0.2s;
}

.testimonial-card:hover {
  border-color: rgba(0,86,210,0.2);
  box-shadow: 0 2px 12px rgba(0,0,0,0.04);
}

.testimonial-quote {
  font-family: 'Source Serif 4', Georgia, serif;
  font-size: 3rem;
  line-height: 1;
  color: var(--brand-primary);
  opacity: 0.25;
  margin-bottom: -0.5rem;
}

.testimonial-text {
  font-size: 0.875rem;
  color: var(--text-primary);
  line-height: 1.6;
}

.testimonial-avatar {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-weight: 600;
  font-size: 0.875rem;
  flex-shrink: 0;
}

/* ===== 数据见证 ===== */
.stats-number {
  font-family: 'Source Serif 4', Georgia, serif;
  font-size: 2.5rem;
  font-weight: 700;
  line-height: 1.1;
  margin-bottom: 0.5rem;
}

.stats-label {
  font-size: 0.9375rem;
  opacity: 0.85;
  line-height: 1.4;
  max-width: 200px;
  margin: 0 auto;
}

/* ===== FAQ 手风琴 ===== */
.home-faq .accordion-item {
  border: none;
  border-bottom: 1px solid var(--border-color);
  background: transparent;
}

.home-faq .accordion-button {
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--text-primary);
  padding: 1rem 0;
  background: transparent;
  box-shadow: none;
}

.home-faq .accordion-button:not(.collapsed) {
  color: var(--brand-primary);
  background: transparent;
}

.home-faq .accordion-button::after {
  background-size: 1rem;
}

.home-faq .accordion-body {
  padding: 0 0 1.25rem 0;
  color: var(--text-muted);
  font-size: 0.875rem;
  line-height: 1.6;
}

/* ===== 响应式 ===== */
@media (max-width: 991.98px) {
  .home-hero-title {
    font-size: 2rem;
  }

  .home-hero-sub {
    font-size: 1rem;
  }

  .home-section-title {
    font-size: 1.375rem;
  }

  .stats-number {
    font-size: 2rem;
  }
}

@media (max-width: 767.98px) {
  .home-hero-title {
    font-size: 1.75rem;
  }

  .min-vh-85 {
    min-height: auto;
  }

  .home-hero {
    padding-top: 3rem;
    padding-bottom: 3rem;
  }

  .home-tabs-nav .nav-link {
    padding: 0.5rem 0.75rem;
    font-size: 0.8125rem;
  }
}