/* =====================
   CSS 变量定义
   ===================== */
:root {
    --primary: #A2D2E2;
    --primary-dark: #8BC0D4;
    --accent: #F5B087;
    --aux-1: #D4BF89;
    --aux-2: #E7CAD3;
    --sidebar-bg: #1B2A4A;
    --sidebar-hover: #253D6A;
    --sidebar-active: #2E4A7A;
    --bg-color: #F5F7FA;
    --card-bg: #FFFFFF;
    --text-primary: #333333;
    --text-secondary: #666666;
    --text-muted: #999999;
    --border-color: #E4E7ED;
    --success: #67C23A;
    --warning: #E6A23C;
    --danger: #F56C6C;
    --info: #909399;
    --shadow: 0 2px 12px rgba(0, 0, 0, 0.1);
    --shadow-light: 0 1px 4px rgba(0, 0, 0, 0.05);
    --radius: 8px;
    --radius-sm: 4px;
}

/* =====================
   基础重置
   ===================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    font-size: 14px;
    color: var(--text-primary);
    background-color: var(--bg-color);
    line-height: 1.5;
}

a {
    text-decoration: none;
    color: inherit;
}

button {
    cursor: pointer;
    border: none;
    outline: none;
    font-family: inherit;
}

input, select, textarea {
    font-family: inherit;
    font-size: inherit;
}

.hidden {
    display: none !important;
}

/* =====================
   登录页
   ===================== */
.login-page {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, var(--sidebar-bg) 0%, #2E4A7A 100%);
}

.login-card {
    width: 380px;
    background: var(--card-bg);
    border-radius: var(--radius);
    padding: 40px;
    box-shadow: var(--shadow);
}

.login-logo {
    text-align: center;
    margin-bottom: 30px;
}

.login-logo h1 {
    font-size: 28px;
    color: var(--sidebar-bg);
    margin-bottom: 8px;
}

.login-logo p {
    color: var(--text-muted);
    font-size: 14px;
}

.login-form .form-group {
    margin-bottom: 20px;
}

.login-form label {
    display: block;
    margin-bottom: 8px;
    color: var(--text-secondary);
    font-size: 14px;
}

.login-form input {
    width: 100%;
    padding: 12px 16px;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-size: 14px;
    transition: border-color 0.2s;
}

.login-form input:focus {
    border-color: var(--primary);
    outline: none;
}

.login-error {
    color: var(--danger);
    font-size: 13px;
    margin-top: 10px;
    text-align: center;
    min-height: 20px;
}

/* =====================
   按钮样式
   ===================== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 10px 20px;
    border-radius: var(--radius-sm);
    font-size: 14px;
    font-weight: 500;
    transition: all 0.2s;
}

.btn-primary {
    background-color: var(--primary);
    color: var(--sidebar-bg);
}

.btn-primary:hover {
    background-color: var(--primary-dark);
}

.btn-default {
    background-color: #fff;
    color: var(--text-secondary);
    border: 1px solid var(--border-color);
}

.btn-default:hover {
    border-color: var(--primary);
    color: var(--primary);
}

.btn-success {
    background-color: var(--success);
    color: #fff;
}

.btn-success:hover {
    background-color: #5daf34;
}

.btn-warning {
    background-color: var(--warning);
    color: #fff;
}

.btn-warning:hover {
    background-color: #d5940c;
}

.btn-danger {
    background-color: var(--danger);
    color: #fff;
}

.btn-danger:hover {
    background-color: #e64242;
}

.btn-sm {
    padding: 6px 12px;
    font-size: 12px;
}

.btn-block {
    width: 100%;
}

/* =====================
   管理员主界面
   ===================== */
.admin-app {
    display: flex;
    min-height: 100vh;
}

/* =====================
   侧边栏
   ===================== */
.sidebar {
    width: 220px;
    background-color: var(--sidebar-bg);
    color: #fff;
    display: flex;
    flex-direction: column;
    position: fixed;
    top: 0;
    left: 0;
    bottom: 0;
    z-index: 100;
}

.sidebar-header {
    padding: 24px 20px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.sidebar-header h2 {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 4px;
}

.sidebar-header p {
    font-size: 12px;
    color: rgba(255, 255, 255, 0.6);
}

.sidebar-nav {
    flex: 1;
    padding: 16px 0;
    overflow-y: auto;
}

.nav-item {
    display: flex;
    align-items: center;
    padding: 12px 20px;
    color: rgba(255, 255, 255, 0.7);
    font-size: 14px;
    transition: all 0.2s;
}

.nav-item:hover {
    background-color: var(--sidebar-hover);
    color: #fff;
}

.nav-item.active {
    background-color: var(--sidebar-active);
    color: #fff;
}

.nav-icon {
    margin-right: 12px;
    font-size: 16px;
}

.nav-divider {
    height: 1px;
    background-color: rgba(255, 255, 255, 0.1);
    margin: 12px 20px;
}

.sidebar-footer {
    padding: 16px 20px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.user-info {
    display: flex;
    align-items: center;
}

.user-avatar {
    width: 32px;
    height: 32px;
    background-color: var(--primary);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--sidebar-bg);
    font-weight: 600;
    margin-right: 10px;
}

.user-name {
    font-size: 14px;
    color: rgba(255, 255, 255, 0.9);
}

.btn-logout {
    background: none;
    color: rgba(255, 255, 255, 0.6);
    font-size: 12px;
    padding: 6px 10px;
    border-radius: var(--radius-sm);
    transition: all 0.2s;
}

.btn-logout:hover {
    background-color: rgba(255, 255, 255, 0.1);
    color: #fff;
}

/* =====================
   主内容区
   ===================== */
.main-content {
    flex: 1;
    margin-left: 220px;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.content-header {
    background-color: var(--card-bg);
    padding: 20px 30px;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.content-header h1 {
    font-size: 20px;
    font-weight: 600;
    color: var(--text-primary);
}

.current-time {
    color: var(--text-muted);
    font-size: 13px;
}

.content-body {
    flex: 1;
    padding: 24px 30px;
}

/* =====================
   卡片
   ===================== */
.card {
    background-color: var(--card-bg);
    border-radius: var(--radius);
    box-shadow: var(--shadow-light);
    padding: 20px;
}

.card-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 16px;
    padding-bottom: 12px;
    border-bottom: 1px solid var(--border-color);
}

.card-title {
    font-size: 16px;
    font-weight: 600;
    color: var(--text-primary);
}

/* =====================
   数据统计卡片
   ===================== */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 20px;
    margin-bottom: 24px;
}

.stat-card {
    background-color: var(--card-bg);
    border-radius: var(--radius);
    padding: 20px;
    box-shadow: var(--shadow-light);
}

.stat-card .stat-icon {
    width: 48px;
    height: 48px;
    border-radius: var(--radius);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 24px;
    margin-bottom: 12px;
}

.stat-card .stat-icon.blue {
    background-color: rgba(162, 210, 226, 0.2);
}

.stat-card .stat-icon.orange {
    background-color: rgba(245, 176, 135, 0.2);
}

.stat-card .stat-icon.green {
    background-color: rgba(103, 194, 58, 0.2);
}

.stat-card .stat-icon.purple {
    background-color: rgba(231, 202, 211, 0.2);
}

.stat-card .stat-value {
    font-size: 28px;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 4px;
}

.stat-card .stat-label {
    font-size: 13px;
    color: var(--text-muted);
}

.stat-card .stat-change {
    font-size: 12px;
    margin-top: 8px;
}

.stat-card .stat-change.up {
    color: var(--success);
}

.stat-card .stat-change.down {
    color: var(--danger);
}

/* =====================
   表格
   ===================== */
.table-container {
    overflow-x: auto;
}

.table {
    width: 100%;
    border-collapse: collapse;
}

.table th,
.table td {
    padding: 14px 16px;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

.table th {
    background-color: #fafafa;
    font-weight: 600;
    color: var(--text-secondary);
    font-size: 13px;
    white-space: nowrap;
}

.table th.sortable {
    cursor: pointer;
}

.table th.sortable:hover {
    color: var(--primary);
}

.table tbody tr {
    transition: background-color 0.15s;
}

.table tbody tr:nth-child(even) {
    background-color: #fafafa;
}

.table tbody tr:hover {
    background-color: rgba(162, 210, 226, 0.1);
}

.table .avatar {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background-color: var(--primary);
    color: var(--sidebar-bg);
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
    font-size: 14px;
}

.table .avatar img {
    width: 100%;
    height: 100%;
    border-radius: 50%;
    object-fit: cover;
}

.table .actions {
    display: flex;
    gap: 8px;
}

/* =====================
   状态标签
   ===================== */
.tag {
    display: inline-flex;
    align-items: center;
    padding: 4px 10px;
    border-radius: 12px;
    font-size: 12px;
    font-weight: 500;
}

.tag-success {
    background-color: rgba(103, 194, 58, 0.1);
    color: var(--success);
}

.tag-warning {
    background-color: rgba(230, 162, 60, 0.1);
    color: var(--warning);
}

.tag-danger {
    background-color: rgba(245, 108, 108, 0.1);
    color: var(--danger);
}

.tag-info {
    background-color: rgba(144, 147, 153, 0.1);
    color: var(--info);
}

.tag-primary {
    background-color: rgba(162, 210, 226, 0.2);
    color: var(--primary-dark);
}

/* =====================
   分页器
   ===================== */
.pagination {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 16px 0;
}

.pagination-info {
    color: var(--text-muted);
    font-size: 13px;
}

.pagination-controls {
    display: flex;
    align-items: center;
    gap: 4px;
}

.pagination-controls button {
    min-width: 32px;
    height: 32px;
    padding: 0 10px;
    background-color: #fff;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-size: 13px;
    color: var(--text-secondary);
    transition: all 0.2s;
}

.pagination-controls button:hover:not(:disabled) {
    border-color: var(--primary);
    color: var(--primary);
}

.pagination-controls button.active {
    background-color: var(--primary);
    border-color: var(--primary);
    color: var(--sidebar-bg);
}

.pagination-controls button:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

/* =====================
   搜索和筛选
   ===================== */
.toolbar {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 20px;
    flex-wrap: wrap;
}

.search-box {
    position: relative;
    flex: 1;
    min-width: 240px;
    max-width: 320px;
}

.search-box input {
    width: 100%;
    padding: 10px 16px 10px 38px;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-size: 14px;
    transition: border-color 0.2s;
}

.search-box input:focus {
    border-color: var(--primary);
    outline: none;
}

.search-box::before {
    content: "🔍";
    position: absolute;
    left: 12px;
    top: 50%;
    transform: translateY(-50%);
    font-size: 14px;
    opacity: 0.5;
}

.filter-select {
    padding: 10px 32px 10px 12px;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-size: 14px;
    background-color: #fff;
    cursor: pointer;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%23999' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 10px center;
}

.filter-select:focus {
    border-color: var(--primary);
    outline: none;
}

/* =====================
   Tab 切换
   ===================== */
.tabs {
    display: flex;
    border-bottom: 1px solid var(--border-color);
    margin-bottom: 20px;
}

.tab-item {
    padding: 12px 24px;
    color: var(--text-muted);
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    position: relative;
    transition: all 0.2s;
}

.tab-item:hover {
    color: var(--primary);
}

.tab-item.active {
    color: var(--primary);
}

.tab-item.active::after {
    content: "";
    position: absolute;
    bottom: -1px;
    left: 0;
    right: 0;
    height: 2px;
    background-color: var(--primary);
}

/* =====================
   弹窗
   ===================== */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: rgba(0, 0, 0, 0.5);
    z-index: 1000;
    display: flex;
    align-items: center;
    justify-content: center;
}

.modal-box {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    z-index: 1001;
    background-color: var(--card-bg);
    border-radius: var(--radius);
    min-width: 400px;
    max-width: 90vw;
    box-shadow: var(--shadow);
}

.modal-header {
    padding: 20px 24px;
    border-bottom: 1px solid var(--border-color);
}

.modal-header h3 {
    font-size: 16px;
    font-weight: 600;
}

.modal-body {
    padding: 24px;
}

.modal-footer {
    padding: 16px 24px;
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: flex-end;
    gap: 12px;
}

/* =====================
   侧边抽屉
   ===================== */
.drawer {
    position: fixed;
    top: 0;
    right: 0;
    bottom: 0;
    width: 480px;
    background-color: var(--card-bg);
    box-shadow: -4px 0 20px rgba(0, 0, 0, 0.15);
    z-index: 1001;
    display: flex;
    flex-direction: column;
    transform: translateX(0);
    transition: transform 0.3s ease;
}

.drawer.hidden {
    transform: translateX(100%);
}

.drawer-header {
    padding: 20px 24px;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.drawer-header h3 {
    font-size: 16px;
    font-weight: 600;
}

.drawer-close {
    width: 32px;
    height: 32px;
    border-radius: 50%;
    background: none;
    font-size: 24px;
    color: var(--text-muted);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s;
}

.drawer-close:hover {
    background-color: var(--bg-color);
    color: var(--text-primary);
}

.drawer-body {
    flex: 1;
    padding: 24px;
    overflow-y: auto;
}

.drawer-section {
    margin-bottom: 24px;
}

.drawer-section-title {
    font-size: 14px;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: 12px;
    padding-bottom: 8px;
    border-bottom: 1px dashed var(--border-color);
}

.drawer-info-row {
    display: flex;
    padding: 8px 0;
    border-bottom: 1px solid var(--border-color);
}

.drawer-info-row:last-child {
    border-bottom: none;
}

.drawer-info-label {
    width: 100px;
    color: var(--text-muted);
    font-size: 13px;
}

.drawer-info-value {
    flex: 1;
    color: var(--text-primary);
    font-size: 14px;
}

/* =====================
   Toast 提示
   ===================== */
.toast-container {
    position: fixed;
    top: 20px;
    right: 20px;
    z-index: 2000;
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.toast {
    padding: 14px 20px;
    border-radius: var(--radius);
    background-color: var(--card-bg);
    box-shadow: var(--shadow);
    display: flex;
    align-items: center;
    gap: 10px;
    animation: slideIn 0.3s ease;
    min-width: 280px;
}

.toast.success {
    border-left: 4px solid var(--success);
}

.toast.error {
    border-left: 4px solid var(--danger);
}

.toast.warning {
    border-left: 4px solid var(--warning);
}

.toast.info {
    border-left: 4px solid var(--info);
}

@keyframes slideIn {
    from {
        transform: translateX(100%);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

@keyframes slideOut {
    from {
        transform: translateX(0);
        opacity: 1;
    }
    to {
        transform: translateX(100%);
        opacity: 0;
    }
}

/* =====================
   Loading 加载
   ===================== */
.loading {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 60px 20px;
}

.loading-spinner {
    width: 40px;
    height: 40px;
    border: 3px solid var(--border-color);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

/* =====================
   空状态
   ===================== */
.empty-state {
    text-align: center;
    padding: 60px 20px;
    color: var(--text-muted);
}

.empty-state-icon {
    font-size: 48px;
    margin-bottom: 16px;
    opacity: 0.5;
}

.empty-state-text {
    font-size: 14px;
}

/* =====================
   快速操作按钮
   ===================== */
.quick-actions {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 12px;
}

.quick-action-btn {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 20px;
    background-color: var(--bg-color);
    border-radius: var(--radius);
    transition: all 0.2s;
}

.quick-action-btn:hover {
    background-color: var(--primary);
    color: var(--sidebar-bg);
}

.quick-action-btn .action-icon {
    font-size: 28px;
    margin-bottom: 8px;
}

.quick-action-btn .action-text {
    font-size: 13px;
    font-weight: 500;
}

/* =====================
   待办列表
   ===================== */
.todo-list {
    list-style: none;
}

.todo-item {
    display: flex;
    align-items: center;
    padding: 12px 0;
    border-bottom: 1px solid var(--border-color);
}

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

.todo-item .todo-content {
    flex: 1;
}

.todo-item .todo-title {
    font-size: 14px;
    color: var(--text-primary);
    margin-bottom: 4px;
}

.todo-item .todo-meta {
    font-size: 12px;
    color: var(--text-muted);
}

.todo-item .todo-actions {
    display: flex;
    gap: 8px;
}

/* =====================
   动态列表
   ===================== */
.activity-list {
    list-style: none;
}

.activity-item {
    display: flex;
    align-items: flex-start;
    padding: 12px 0;
    border-bottom: 1px solid var(--border-color);
}

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

.activity-avatar {
    width: 32px;
    height: 32px;
    border-radius: 50%;
    background-color: var(--primary);
    color: var(--sidebar-bg);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 12px;
    font-weight: 600;
    margin-right: 12px;
    flex-shrink: 0;
}

.activity-content {
    flex: 1;
}

.activity-text {
    font-size: 14px;
    color: var(--text-primary);
    margin-bottom: 2px;
}

.activity-time {
    font-size: 12px;
    color: var(--text-muted);
}

/* =====================
   表单样式
   ===================== */
.form-row {
    display: flex;
    gap: 16px;
    margin-bottom: 16px;
}

.form-item {
    flex: 1;
}

.form-label {
    display: block;
    margin-bottom: 8px;
    font-size: 13px;
    color: var(--text-secondary);
}

.form-input {
    width: 100%;
    padding: 10px 12px;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-size: 14px;
    transition: border-color 0.2s;
}

.form-input:focus {
    border-color: var(--primary);
    outline: none;
}

/* =====================
   复制按钮
   ===================== */
.copy-btn {
    padding: 4px 8px;
    background-color: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-size: 12px;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.2s;
    margin-left: 8px;
}

.copy-btn:hover {
    border-color: var(--primary);
    color: var(--primary);
}

.copy-btn.copied {
    background-color: var(--success);
    border-color: var(--success);
    color: #fff;
}

/* =====================
   图表容器
   ===================== */
.chart-container {
    height: 300px;
    background-color: var(--bg-color);
    border-radius: var(--radius);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-muted);
}

/* =====================
   网格布局
   ===================== */
.grid-2 {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 20px;
}

/* =====================
   响应式
   ===================== */
@media (max-width: 1200px) {
    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 1024px) {
    .sidebar {
        width: 180px;
    }
    
    .main-content {
        margin-left: 180px;
    }
    
    .drawer {
        width: 400px;
    }
}

/* =====================
   徽章
   ===================== */
.badge {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-width: 18px;
    height: 18px;
    padding: 0 6px;
    border-radius: 9px;
    background-color: var(--danger);
    color: #fff;
    font-size: 11px;
    font-weight: 600;
}

.nav-item .badge {
    margin-left: auto;
}

/* =====================
   佣金卡片
   ===================== */
.commission-card {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    border-radius: var(--radius);
    padding: 20px;
    color: var(--sidebar-bg);
}

.commission-card .commission-label {
    font-size: 13px;
    opacity: 0.8;
    margin-bottom: 8px;
}

.commission-card .commission-value {
    font-size: 32px;
    font-weight: 700;
}

/* =====================
   进度条
   ===================== */
.progress-bar {
    width: 100%;
    height: 8px;
    background-color: var(--border-color);
    border-radius: 4px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background-color: var(--primary);
    border-radius: 4px;
    transition: width 0.3s ease;
}


/* =====================
   课程卡片样式
   ===================== */
.course-card {
    background-color: var(--card-bg);
    border-radius: 12px;
    overflow: hidden;
    box-shadow: var(--shadow-light);
    transition: all 0.2s ease;
    border: 1px solid var(--border-color);
}

.course-card:hover {
    box-shadow: var(--shadow);
    transform: translateY(-2px);
}

.course-card-header {
    padding: 20px;
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
}

.course-level-badge {
    position: absolute;
    top: 8px;
    right: 8px;
    padding: 2px 8px;
    border-radius: 10px;
    font-size: 11px;
    font-weight: 500;
}

.course-level-badge.level-required {
    background-color: #FCE4EC;
    color: #E91E63;
}

.course-level-badge.level-elective {
    background-color: #E3F2FD;
    color: #1976D2;
}

.course-card-body {
    padding: 16px;
}

/* 课时列表样式 */
.lesson-row {
    display: flex;
    align-items: center;
    padding: 12px;
    border-bottom: 1px solid var(--border-color);
    cursor: pointer;
    transition: background-color 0.15s;
}

.lesson-row:hover {
    background-color: var(--bg-color);
}

.lesson-row:last-child {
    border-bottom: none;
}

.lesson-num {
    width: 28px;
    height: 28px;
    border-radius: 50%;
    background-color: var(--primary);
    color: var(--sidebar-bg);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 12px;
    font-weight: 600;
    margin-right: 12px;
    flex-shrink: 0;
}

.lesson-info {
    flex: 1;
    display: flex;
    flex-direction: column;
}

.lesson-title {
    font-size: 13px;
    color: var(--text-primary);
    margin-bottom: 2px;
}

.lesson-duration {
    font-size: 11px;
    color: var(--text-muted);
}

.lesson-arrow {
    font-size: 18px;
    color: var(--text-muted);
    margin-left: 8px;
}

/* 课时详情内容 */
.lesson-detail-content {
    max-height: 60vh;
    overflow-y: auto;
}