/**
 * 华深教育 - 前台样式表
 */

/* ===== 基础样式 ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #3498db;
    --primary-dark: #2980b9;
    --secondary-color: #2ecc71;
    --danger-color: #e74c3c;
    --warning-color: #f39c12;
    --dark-color: #2c3e50;
    --gray-color: #95a5a6;
    --light-gray: #ecf0f1;
    --border-color: #ddd;
    --text-color: #333;
    --text-muted: #666;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    font-size: 14px;
    line-height: 1.6;
    color: var(--text-color);
    background-color: #f5f7fa;
}

a {
    color: var(--primary-color);
    text-decoration: none;
    transition: color 0.3s;
}

a:hover {
    color: var(--primary-dark);
}

img {
    max-width: 100%;
    height: auto;
}

/* ===== 容器 ===== */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* ===== 头部 ===== */
.site-header {
    background: #fff;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 15px 0;
}

.logo h1 {
    font-size: 24px;
    color: var(--primary-color);
    font-weight: 700;
}

.logo a {
    color: inherit;
}

.main-nav ul {
    display: flex;
    list-style: none;
    gap: 30px;
}

.main-nav a {
    color: var(--text-color);
    font-weight: 500;
    padding: 8px 0;
    position: relative;
}

.main-nav a.active,
.main-nav a:hover {
    color: var(--primary-color);
}

.main-nav a.active::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--primary-color);
}

/* 下拉菜单 */
.dropdown {
    position: relative;
}

.dropdown-content {
    display: none;
    position: absolute;
    top: 100%;
    left: 50%;
    transform: translateX(-50%);
    background: #fff;
    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
    border-radius: 8px;
    min-width: 160px;
    z-index: 100;
}

.dropdown:hover .dropdown-content {
    display: block;
}

.dropdown-content a {
    display: block;
    padding: 10px 20px;
    white-space: nowrap;
}

.dropdown-content a:hover {
    background: var(--light-gray);
}

/* 用户菜单 */
.header-right {
    display: flex;
    align-items: center;
    gap: 15px;
}

.auth-links {
    display: flex;
    gap: 10px;
}

.user-menu {
    position: relative;
    display: flex;
    align-items: center;
    gap: 10px;
    cursor: pointer;
}

.user-name {
    font-weight: 500;
}

.user-points {
    background: var(--primary-color);
    color: #fff;
    padding: 4px 10px;
    border-radius: 20px;
    font-size: 12px;
}

.user-dropdown {
    display: none;
    position: absolute;
    top: 100%;
    right: 0;
    background: #fff;
    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
    border-radius: 8px;
    min-width: 150px;
    z-index: 100;
}

.user-menu:hover .user-dropdown {
    display: block;
}

.user-dropdown a {
    display: block;
    padding: 10px 15px;
    color: var(--text-color);
}

.user-dropdown a:hover {
    background: var(--light-gray);
}

/* 移动端菜单按钮 */
.mobile-menu-btn {
    display: none;
    background: none;
    border: none;
    font-size: 24px;
    cursor: pointer;
}

/* ===== 按钮 ===== */
.btn {
    display: inline-block;
    padding: 10px 20px;
    border: none;
    border-radius: 6px;
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s;
    text-align: center;
}

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

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

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

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

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

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

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

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

.btn-block {
    display: block;
    width: 100%;
}

.btn-lg {
    padding: 14px 28px;
    font-size: 16px;
}

/* ===== 表单 ===== */
.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 6px;
    font-weight: 500;
    color: var(--text-color);
}

.form-group input[type="text"],
.form-group input[type="email"],
.form-group input[type="password"],
.form-group input[type="tel"],
.form-group input[type="number"],
.form-group textarea,
.form-group select {
    width: 100%;
    padding: 10px 12px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    font-size: 14px;
    transition: border-color 0.3s;
}

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

.form-group textarea {
    resize: vertical;
}

.form-help {
    display: block;
    margin-top: 4px;
    font-size: 12px;
    color: var(--text-muted);
}

.required {
    color: var(--danger-color);
}

.checkbox-label {
    display: flex;
    align-items: center;
    gap: 8px;
    cursor: pointer;
}

.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
}

/* ===== 提示框 ===== */
.alert {
    padding: 12px 16px;
    border-radius: 6px;
    margin-bottom: 20px;
}

.alert-success {
    background: #d4edda;
    color: #155724;
    border: 1px solid #c3e6cb;
}

.alert-error {
    background: #f8d7da;
    color: #721c24;
    border: 1px solid #f5c6cb;
}

.alert-warning {
    background: #fff3cd;
    color: #856404;
    border: 1px solid #ffeeba;
}

/* ===== Hero区域 ===== */
.hero {
    background: linear-gradient(135deg, var(--primary-color) 0%, #667eea 100%);
    color: #fff;
    padding: 80px 0;
    text-align: center;
}

.hero h1 {
    font-size: 48px;
    margin-bottom: 20px;
}

.hero-subtitle {
    font-size: 20px;
    opacity: 0.9;
    margin-bottom: 30px;
}

.hero-search {
    max-width: 600px;
    margin: 0 auto;
}

.hero-search form {
    display: flex;
    gap: 10px;
}

.hero-search input {
    flex: 1;
    padding: 14px 20px;
    border: none;
    border-radius: 30px;
    font-size: 16px;
}

.hero-search button {
    padding: 14px 30px;
    border-radius: 30px;
}

/* ===== 特性 ===== */
.features {
    padding: 60px 0;
    background: #fff;
}

.feature-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 30px;
}

.feature-item {
    text-align: center;
    padding: 30px 20px;
}

.feature-icon {
    font-size: 48px;
    margin-bottom: 15px;
}

.feature-item h3 {
    margin-bottom: 10px;
    color: var(--dark-color);
}

/* ===== 分类 ===== */
.categories-section,
.courses-section {
    padding: 60px 0;
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 30px;
}

.section-header h2 {
    font-size: 28px;
    color: var(--dark-color);
}

.view-more {
    color: var(--primary-color);
    font-weight: 500;
}

.category-grid {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 20px;
}

.category-card {
    background: #fff;
    padding: 25px 20px;
    border-radius: 12px;
    text-align: center;
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
    transition: transform 0.3s, box-shadow 0.3s;
}

.category-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(0,0,0,0.1);
}

.category-icon {
    font-size: 36px;
    margin-bottom: 12px;
}

.category-card h3 {
    font-size: 16px;
    margin-bottom: 8px;
    color: var(--dark-color);
}

.category-card p {
    font-size: 12px;
    color: var(--text-muted);
}

/* ===== 课程 ===== */
.course-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 25px;
}

.course-card {
    background: #fff;
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
    transition: transform 0.3s, box-shadow 0.3s;
}

.course-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(0,0,0,0.1);
}

.course-cover {
    position: relative;
    height: 160px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    overflow: hidden;
}

.course-cover img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.course-cover-placeholder {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 100%;
    height: 100%;
    font-size: 48px;
    color: #fff;
}

.course-cover-placeholder.large {
    font-size: 72px;
}

.course-points {
    position: absolute;
    bottom: 10px;
    right: 10px;
    background: rgba(0,0,0,0.7);
    color: #fff;
    padding: 4px 10px;
    border-radius: 20px;
    font-size: 12px;
}

.course-info {
    padding: 15px;
}

.course-category {
    font-size: 12px;
    color: var(--primary-color);
}

.course-info h3 {
    font-size: 16px;
    margin: 6px 0;
    line-height: 1.4;
}

.course-info h3 a {
    color: var(--dark-color);
}

.course-info h3 a:hover {
    color: var(--primary-color);
}

.course-desc {
    font-size: 12px;
    color: var(--text-muted);
    margin-bottom: 10px;
}

.course-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

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

/* ===== 关于预览 ===== */
.about-preview {
    background: linear-gradient(135deg, var(--dark-color) 0%, #34495e 100%);
    color: #fff;
    padding: 60px 0;
}

.about-content {
    display: flex;
    gap: 60px;
    align-items: center;
}

.about-text h2 {
    font-size: 32px;
    margin-bottom: 20px;
}

.about-text p {
    margin-bottom: 20px;
    opacity: 0.9;
}

.about-stats {
    display: flex;
    gap: 40px;
}

.stat-item {
    text-align: center;
}

.stat-number {
    font-size: 48px;
    font-weight: 700;
    color: var(--primary-color);
}

.stat-label {
    font-size: 14px;
    opacity: 0.8;
}

/* ===== 登录/注册 ===== */
.auth-container {
    min-height: calc(100vh - 200px);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 40px 20px;
}

.auth-box {
    background: #fff;
    padding: 40px;
    border-radius: 12px;
    box-shadow: 0 10px 40px rgba(0,0,0,0.1);
    width: 100%;
    max-width: 420px;
}

.auth-header {
    text-align: center;
    margin-bottom: 30px;
}

.auth-header h2 {
    font-size: 24px;
    color: var(--dark-color);
    margin-bottom: 8px;
}

.auth-header p {
    color: var(--text-muted);
}

.auth-footer {
    text-align: center;
    margin-top: 20px;
    padding-top: 20px;
    border-top: 1px solid var(--border-color);
}

/* ===== 课程详情 ===== */
.course-detail-page {
    padding: 30px 0;
}

.course-detail-header {
    margin-bottom: 20px;
}

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

.breadcrumb a {
    color: var(--text-muted);
}

.breadcrumb a:hover {
    color: var(--primary-color);
}

.course-detail-content {
    display: grid;
    grid-template-columns: 1fr 350px;
    gap: 30px;
}

.course-detail-main {
    background: #fff;
    border-radius: 12px;
    padding: 30px;
}

.course-detail-info h1 {
    font-size: 28px;
    margin-bottom: 15px;
}

.course-meta-info {
    display: flex;
    gap: 15px;
    margin-bottom: 20px;
    flex-wrap: wrap;
}

.category-tag {
    background: var(--light-gray);
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 12px;
}

.download-info,
.upload-time {
    font-size: 14px;
    color: var(--text-muted);
}

.course-section {
    margin-top: 25px;
}

.course-section h3 {
    font-size: 18px;
    margin-bottom: 10px;
    color: var(--dark-color);
}

.course-sidebar-card {
    background: #fff;
    border-radius: 12px;
    padding: 20px;
    position: sticky;
    top: 90px;
}

.course-cover-preview {
    height: 200px;
    border-radius: 8px;
    overflow: hidden;
    margin-bottom: 20px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

.course-file-info {
    margin-bottom: 20px;
}

.file-info-item {
    display: flex;
    justify-content: space-between;
    padding: 10px 0;
    border-bottom: 1px solid var(--border-color);
}

.file-info-item .label {
    color: var(--text-muted);
}

.file-info-item .points {
    color: var(--primary-color);
    font-weight: 600;
}

.course-action {
    margin-bottom: 15px;
}

.user-points-info {
    font-size: 14px;
    color: var(--text-muted);
    margin-bottom: 10px;
}

.points-warning {
    color: var(--danger-color);
    margin-bottom: 10px;
}

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

/* ===== 用户中心 ===== */
.user-center-page {
    padding: 30px 0;
}

.user-center-layout {
    display: grid;
    grid-template-columns: 250px 1fr;
    gap: 30px;
}

.user-sidebar {
    background: #fff;
    border-radius: 12px;
    overflow: hidden;
}

.user-sidebar-header {
    background: linear-gradient(135deg, var(--primary-color) 0%, #667eea 100%);
    color: #fff;
    padding: 25px 20px;
    text-align: center;
}

.user-avatar {
    width: 80px;
    height: 80px;
    border-radius: 50%;
    background: rgba(255,255,255,0.2);
    margin: 0 auto 15px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 32px;
    font-weight: 700;
}

.user-sidebar-header h3 {
    margin-bottom: 5px;
}

.user-role {
    font-size: 12px;
    opacity: 0.8;
}

.user-nav {
    padding: 15px 0;
}

.user-nav a {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 12px 20px;
    color: var(--text-color);
}

.user-nav a:hover,
.user-nav a.active {
    background: var(--light-gray);
    color: var(--primary-color);
}

.user-nav a span {
    font-size: 18px;
}

.user-main {
    background: #fff;
    border-radius: 12px;
    padding: 25px;
}

.user-content-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 25px;
    padding-bottom: 15px;
    border-bottom: 1px solid var(--border-color);
}

.user-content-header h2 {
    font-size: 22px;
}

.user-info-card {
    margin-bottom: 25px;
}

.info-section {
    margin-bottom: 30px;
}

.info-section h3 {
    font-size: 16px;
    margin-bottom: 15px;
    color: var(--dark-color);
}

.info-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 15px;
}

.info-item {
    display: flex;
    gap: 10px;
}

.info-item label {
    color: var(--text-muted);
}

.points-highlight {
    color: var(--primary-color);
    font-weight: 600;
}

.referral-code {
    background: var(--light-gray);
    padding: 2px 8px;
    border-radius: 4px;
    font-family: monospace;
}

.quick-actions {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 15px;
}

.action-card {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 25px 15px;
    background: var(--light-gray);
    border-radius: 12px;
    text-align: center;
    transition: transform 0.3s;
}

.action-card:hover {
    transform: translateY(-3px);
    background: var(--primary-color);
    color: #fff;
}

.action-icon {
    font-size: 32px;
    margin-bottom: 10px;
}

.action-text {
    font-weight: 500;
}

/* ===== 下载列表 ===== */
.download-total {
    color: var(--text-muted);
}

.download-list {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.download-item {
    display: flex;
    align-items: center;
    gap: 15px;
    padding: 15px;
    background: var(--light-gray);
    border-radius: 10px;
}

.download-cover {
    width: 80px;
    height: 60px;
    border-radius: 6px;
    overflow: hidden;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

.download-cover-placeholder {
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 24px;
    color: #fff;
}

.download-info {
    flex: 1;
}

.download-info h4 {
    font-size: 15px;
    margin-bottom: 5px;
}

.download-meta {
    display: flex;
    gap: 15px;
    font-size: 12px;
    color: var(--text-muted);
}

.free-tag {
    background: var(--secondary-color);
    color: #fff;
    padding: 2px 6px;
    border-radius: 4px;
}

/* ===== 推荐 ===== */
.referral-stats-card {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
    margin-bottom: 25px;
}

.stat-item-large {
    background: linear-gradient(135deg, var(--primary-color) 0%, #667eea 100%);
    color: #fff;
    padding: 25px;
    border-radius: 12px;
    display: flex;
    align-items: center;
    gap: 15px;
}

.stat-icon {
    font-size: 36px;
}

.stat-content {
    display: flex;
    flex-direction: column;
}

.stat-content .stat-number {
    font-size: 32px;
    font-weight: 700;
    color: #fff;
}

.stat-content .stat-label {
    font-size: 14px;
    opacity: 0.9;
}

.referral-link-card {
    background: var(--light-gray);
    padding: 25px;
    border-radius: 12px;
    margin-bottom: 25px;
}

.referral-link-card h3 {
    margin-bottom: 10px;
}

.referral-desc {
    color: var(--text-muted);
    margin-bottom: 15px;
}

.referral-link-box {
    display: flex;
    gap: 10px;
    margin-bottom: 15px;
}

.referral-link-box input {
    flex: 1;
    padding: 12px 15px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    background: #fff;
}

.referral-code-box {
    display: flex;
    align-items: center;
    gap: 10px;
}

.referral-code-box strong {
    font-size: 18px;
    color: var(--primary-color);
    font-family: monospace;
}

.referral-list-card {
    background: var(--light-gray);
    padding: 25px;
    border-radius: 12px;
    margin-bottom: 25px;
}

.referral-list-card h3 {
    margin-bottom: 15px;
}

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

.referral-table th,
.referral-table td {
    padding: 12px;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

.referral-table th {
    font-weight: 500;
    color: var(--text-muted);
}

.referral-rules {
    background: #fff;
    padding: 20px;
    border-radius: 12px;
}

.referral-rules h3 {
    margin-bottom: 15px;
}

.referral-rules ul {
    list-style: none;
}

.referral-rules li {
    padding: 8px 0;
    padding-left: 20px;
    position: relative;
}

.referral-rules li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--secondary-color);
}

.empty-referrals {
    text-align: center;
    padding: 30px;
    color: var(--text-muted);
}

.empty-referrals .tips {
    font-size: 13px;
}

/* ===== 充值 ===== */
.recharge-info-card,
.recharge-form-card {
    background: #fff;
    border-radius: 12px;
    padding: 25px;
    margin-bottom: 25px;
}

.recharge-info-card h2,
.recharge-form-card h2 {
    font-size: 18px;
    margin-bottom: 20px;
}

.user-info-box {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 15px;
}

.info-item {
    padding: 15px;
    background: var(--light-gray);
    border-radius: 8px;
}

.amount-options {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 15px;
    margin-bottom: 25px;
}

.amount-option {
    cursor: pointer;
}

.amount-option input {
    display: none;
}

.amount-box {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 20px;
    border: 2px solid var(--border-color);
    border-radius: 10px;
    transition: all 0.3s;
}

.amount-option:hover .amount-box {
    border-color: var(--primary-color);
}

.amount-option input:checked + .amount-box {
    border-color: var(--primary-color);
    background: rgba(52, 152, 219, 0.1);
}

.amount-box .amount {
    font-size: 20px;
    font-weight: 600;
    color: var(--dark-color);
}

.amount-box .points {
    font-size: 13px;
    color: var(--primary-color);
    margin-top: 5px;
}

.payment-methods h3 {
    font-size: 16px;
    margin-bottom: 15px;
}

.payment-options {
    display: flex;
    gap: 15px;
    margin-bottom: 25px;
}

.payment-option {
    cursor: pointer;
}

.payment-option input {
    display: none;
}

.payment-box {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 15px 25px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
}

.payment-option:hover .payment-box {
    border-color: var(--primary-color);
}

.payment-option input:checked + .payment-box {
    border-color: var(--primary-color);
    background: rgba(52, 152, 219, 0.1);
}

.recharge-tips {
    margin-top: 20px;
    font-size: 13px;
    color: var(--text-muted);
    line-height: 1.8;
}

/* ===== 分页 ===== */
.pagination {
    display: flex;
    justify-content: center;
    gap: 5px;
    margin-top: 30px;
}

.pagination a,
.pagination span {
    padding: 8px 14px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    font-size: 14px;
    color: var(--text-color);
}

.pagination a:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
}

.pagination a.active {
    background: var(--primary-color);
    border-color: var(--primary-color);
    color: #fff;
}

.pagination .ellipsis {
    border: none;
    color: var(--text-muted);
}

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

.empty-icon {
    font-size: 64px;
    margin-bottom: 15px;
}

.empty-state h3 {
    font-size: 20px;
    margin-bottom: 10px;
    color: var(--dark-color);
}

.empty-state p {
    color: var(--text-muted);
    margin-bottom: 20px;
}

/* ===== 课程列表页 ===== */
.courses-page {
    padding: 30px 0;
}

.page-header {
    margin-bottom: 25px;
}

.page-header h1 {
    font-size: 28px;
    margin-bottom: 5px;
}

.course-count {
    color: var(--text-muted);
}

.courses-layout {
    display: grid;
    grid-template-columns: 220px 1fr;
    gap: 30px;
}

.courses-sidebar {
    background: #fff;
    border-radius: 12px;
    padding: 20px;
    height: fit-content;
}

.sidebar-section h3 {
    font-size: 16px;
    margin-bottom: 15px;
    padding-bottom: 10px;
    border-bottom: 1px solid var(--border-color);
}

.category-list {
    list-style: none;
}

.category-list li {
    margin-bottom: 5px;
}

.category-list a {
    display: block;
    padding: 10px 12px;
    color: var(--text-color);
    border-radius: 6px;
}

.category-list li:hover a,
.category-list li.active a {
    background: var(--light-gray);
    color: var(--primary-color);
}

.courses-toolbar {
    margin-bottom: 20px;
}

.search-form {
    display: flex;
    gap: 10px;
}

.search-form input {
    flex: 1;
    padding: 10px 15px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
}

/* ===== 页面 ===== */
.about-page,
.contact-page {
    padding: 30px 0;
}

.about-content,
.contact-content {
    max-width: 900px;
    margin: 0 auto;
}

.about-section,
.contact-info-section {
    background: #fff;
    padding: 30px;
    border-radius: 12px;
    margin-bottom: 25px;
}

.about-section h2,
.contact-info-section h2 {
    font-size: 22px;
    margin-bottom: 20px;
    padding-bottom: 10px;
    border-bottom: 2px solid var(--primary-color);
}

.about-text {
    line-height: 1.8;
    color: var(--text-muted);
}

.advantages-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 25px;
    margin-top: 25px;
}

.advantage-item {
    text-align: center;
    padding: 25px;
    background: var(--light-gray);
    border-radius: 12px;
}

.advantage-icon {
    font-size: 40px;
    margin-bottom: 15px;
}

.timeline {
    margin-top: 30px;
}

.timeline-item {
    display: flex;
    gap: 20px;
    margin-bottom: 25px;
}

.timeline-date {
    width: 80px;
    font-weight: 600;
    color: var(--primary-color);
}

.timeline-content {
    flex: 1;
    padding-left: 20px;
    border-left: 2px solid var(--border-color);
}

.timeline-content h4 {
    margin-bottom: 5px;
}

.contact-info-box {
    padding: 20px;
    background: var(--light-gray);
    border-radius: 10px;
    line-height: 1.8;
}

.contact-hours {
    margin-top: 20px;
}

.contact-hours h3 {
    margin-bottom: 10px;
}

.contact-form-section {
    background: #fff;
    padding: 30px;
    border-radius: 12px;
}

.contact-form-section h2 {
    font-size: 22px;
    margin-bottom: 20px;
}

.contact-hours h3 {
    font-size: 16px;
}

/* ===== 页脚 ===== */
.site-footer {
    background: var(--dark-color);
    color: #fff;
    padding: 50px 0 20px;
    margin-top: 60px;
}

.footer-content {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 40px;
    margin-bottom: 40px;
}

.footer-section h3,
.footer-section h4 {
    margin-bottom: 20px;
}

.footer-section ul {
    list-style: none;
}

.footer-section a {
    display: block;
    padding: 5px 0;
    color: rgba(255,255,255,0.7);
}

.footer-section a:hover {
    color: #fff;
}

.footer-bottom {
    text-align: center;
    padding-top: 20px;
    border-top: 1px solid rgba(255,255,255,0.1);
    color: rgba(255,255,255,0.5);
}

/* ===== 响应式 ===== */
@media (max-width: 1024px) {
    .feature-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .category-grid {
        grid-template-columns: repeat(3, 1fr);
    }
    
    .course-grid {
        grid-template-columns: repeat(3, 1fr);
    }
    
    .footer-content {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    .header-content {
        flex-wrap: wrap;
    }
    
    .main-nav {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: #fff;
        padding: 20px;
        box-shadow: 0 4px 10px rgba(0,0,0,0.1);
    }
    
    .main-nav.active {
        display: block;
    }
    
    .main-nav ul {
        flex-direction: column;
        gap: 0;
    }
    
    .main-nav a {
        display: block;
        padding: 12px 0;
    }
    
    .mobile-menu-btn {
        display: block;
    }
    
    .hero h1 {
        font-size: 32px;
    }
    
    .feature-grid,
    .category-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .course-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .about-content {
        flex-direction: column;
    }
    
    .user-center-layout {
        grid-template-columns: 1fr;
    }
    
    .courses-layout {
        grid-template-columns: 1fr;
    }
    
    .courses-sidebar {
        order: -1;
    }
    
    .course-detail-content {
        grid-template-columns: 1fr;
    }
    
    .form-row {
        grid-template-columns: 1fr;
    }
    
    .referral-stats-card {
        grid-template-columns: 1fr;
    }
    
    .quick-actions {
        grid-template-columns: 1fr;
    }
    
    .amount-options {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 15px;
    }
    
    .feature-grid,
    .category-grid,
    .course-grid {
        grid-template-columns: 1fr;
    }
    
    .about-stats {
        flex-direction: column;
        gap: 20px;
    }
    
    .user-info-box {
        grid-template-columns: 1fr;
    }
    
    .info-grid {
        grid-template-columns: 1fr;
    }
    
    .advantages-grid {
        grid-template-columns: 1fr;
    }
    
    .payment-options {
        flex-direction: column;
    }
}