:root {
    --primary-color: #007AFF;
    --secondary-color: #34C759;
    --accent-color: #FF9500;
    --background-color: #F2F2F7;
    --card-bg: #FFFFFF;
    --text-primary: #1C1C1E;
    --text-secondary: #8E8E93;
    --border-color: #D1D1D6;
    --shadow-color: rgba(0, 0, 0, 0.05);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    -webkit-tap-highlight-color: transparent;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--background-color);
    color: var(--text-primary);
    padding-top: 3rem;
    padding-bottom: 80px;
}

/* 顶部导航栏 */
.top-nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: 3rem;
    background: var(--card-bg);
    display: flex;
    align-items: center;
    padding: 0 16px;
    z-index: 1000;
    border-bottom: 1px solid var(--border-color);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
}

.back-btn {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    background: #f1f5f9;
    color: var(--text-primary);
    font-size: 18px;
}

.page-title {
    flex: 1;
    text-align: center;
    font-size: 18px;
    font-weight: 600;
    margin: 0 16px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.menu-btn {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    background: #f1f5f9;
    color: var(--text-primary);
    font-size: 18px;
}

/* 搜索栏 */
.search-container {
    padding: 16px;
    background: var(--card-bg);
    border-bottom: 1px solid var(--border-color);
}

.search-bar {
    display: flex;
    align-items: center;
    background: var(--background-color);
    border-radius: 10px;
    padding: 8px 12px;
}

.search-bar input {
    flex: 1;
    border: none;
    background: transparent;
    padding: 4px 8px;
    font-size: 15px;
    outline: none;
}

/* 统计卡片 */
.stats-container {
    display: flex;
    padding: 16px;
    gap: 12px;
    background: var(--card-bg);
    border-bottom: 1px solid var(--border-color);
}

.stat-card {
    flex: 1;
    text-align: center;
    padding: 12px 0;
}

.stat-number {
    font-size: 20px;
    font-weight: 700;
    margin-bottom: 4px;
}

.stat-number.primary {
    color: var(--primary-color);
}

.stat-number.secondary {
    color: var(--secondary-color);
}

.stat-number.accent {
    color: var(--accent-color);
}

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

/* 分类导航 */
.category-nav {
    display: flex;
    background: var(--card-bg);
    padding: 0 16px;
    border-bottom: 1px solid var(--border-color);
    overflow-x: auto;
}

.category-nav::-webkit-scrollbar {
    display: none;
}

.category-item {
    padding: 16px 12px;
    font-size: 15px;
    white-space: nowrap;
    position: relative;
}

.category-item.active {
    font-weight: 600;
}

.category-item.active::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: var(--primary-color);
    border-radius: 3px 3px 0 0;
}

/* 课程列表 */
.course-section {
    margin: 16px;
}

.section-header {
    display: flex;
    align-items: center;
    margin-bottom: 16px;
}

.section-title {
    font-size: 19px;
    font-weight: 600;
    margin-right: 8px;
}

.section-subtitle {
    font-size: 13px;
    color: var(--text-secondary);
}

.course-list {
    display: grid;
    gap: 12px;
}

.course-card {
    background: var(--card-bg);
    border-radius: 12px;
    padding: 16px;
    box-shadow: 0 2px 8px var(--shadow-color);
    transition: transform 0.2s ease;
}

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

.course-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 12px;
}

.course-name {
    font-size: 17px;
    font-weight: 600;
    margin-right: 8px;
}

.level-tag {
    font-size: 12px;
    padding: 4px 8px;
    border-radius: 8px;
    font-weight: 500;
}

.level-primary {
    background: rgba(0, 122, 255, 0.1);
    color: var(--primary-color);
}

.level-secondary {
    background: rgba(52, 199, 89, 0.1);
    color: var(--secondary-color);
}

.level-accent {
    background: rgba(255, 149, 0, 0.1);
    color: var(--accent-color);
}

.course-desc {
    font-size: 14px;
    color: var(--text-secondary);
    margin-bottom: 16px;
    line-height: 1.4;
}

.subject-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 16px;
}

.subject-tag {
    font-size: 12px;
    padding: 4px 10px;
    border-radius: 20px;
    display: flex;
    align-items: center;
}

.tag-chinese {
    background: rgba(0, 122, 255, 0.1);
    color: var(--primary-color);
}

.tag-math {
    background: rgba(52, 199, 89, 0.1);
    color: var(--secondary-color);
}

.tag-english {
    background: rgba(255, 149, 0, 0.1);
    color: var(--accent-color);
}

.tag-physics {
    background: rgba(175, 82, 222, 0.1);
    color: #AF52DE;
}

.tag-chemistry {
    background: rgba(0, 199, 190, 0.1);
    color: #00C7BE;
}

.tag-biology {
    background: rgba(255, 59, 48, 0.1);
    color: #FF3B30;
}

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

.course-meta {
    display: flex;
    gap: 16px;
}

.meta-item {
    display: flex;
    align-items: center;
    font-size: 13px;
    color: var(--text-secondary);
}

.meta-item i {
    margin-right: 4px;
    font-size: 12px;
}

.rating {
    color: #FF9500;
}

.view-btn {
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: 8px;
    padding: 8px 16px;
    font-size: 14px;
    font-weight: 500;
    display: flex;
    align-items: center;
}

.view-btn i {
    margin-right: 4px;
    font-size: 12px;
}

/* 底部导航 */
.bottom-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    height: 80px;
    background: var(--card-bg);
    display: flex;
    justify-content: space-around;
    align-items: center;
    padding: 12px 0;
    border-top: 1px solid var(--border-color);
    z-index: 1000;
}

.nav-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-decoration: none;
    color: var(--text-secondary);
}

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

.nav-icon {
    font-size: 22px;
    margin-bottom: 4px;
}

.nav-label {
    font-size: 10px;
    font-weight: 500;
}

/* 装饰元素 */
.floating-element {
    position: relative;
    overflow: hidden;
}

.floating-element::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(0, 122, 255, 0.05) 0%, transparent 70%);
    z-index: 0;
}

.floating-element > * {
    position: relative;
    z-index: 1;
}

/* 添加.pt-16样式 */
.pt-16 {
    padding-top: 0.5rem;
}