/* 基础布局 */
html, 
body {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    margin: 0;
    padding: 0;
}

main {
    flex: 1 0 auto;
    padding-top: 80px;
    background-color: var(--background-color);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* 页脚间距 */
.main-footer {
    margin-top: 4rem;
    padding-top: 3rem;
}

/* 分区样式 */
.section-divider {
    margin-top: 3rem;  /* 减少顶部间距 */
    padding-top: 1rem;
    position: relative;
}

.section-divider::before {
    content: '';
    position: absolute;
    top: -1.5rem;
    left: 0;
    right: 0;
    height: 1px;
    background: var(--border-color);
    opacity: 0.2;
}

.section-divider .section-title {
    margin-bottom: 2rem;
}

/* 课程列表页面样式 */
.section-title {
    font-size: 1.75rem;
    font-weight: 600;
    color: var(--text-color);
    margin-bottom: 1.5rem;
    padding-top: 0.5rem;
}

/* 分类区域样式 */
.categories-section {
    margin-bottom: 3rem;
}

/* 搜索栏样式 */
.search-section {
    margin: 2rem 0;
}

.search-section .input-group {
    display: flex;
    max-width: 600px;
    margin: 0 auto;
}

.search-section input {
    flex: 1;
    padding: 1rem 1.5rem;
    border: 1px solid var(--border-color);
    border-radius: 50px 0 0 50px;
    font-size: 1rem;
    outline: none;
}

.search-section button {
    padding: 1rem 2rem;
    background-color: var(--primary-color);
    border: none;
    border-radius: 0 50px 50px 0;
    color: white;
    cursor: pointer;
    transition: background-color 0.3s ease;
}

.search-section button:hover {
    background-color: #2577b5;
}

.search-section i {
    font-size: 1.2rem;
}

/* 分类卡片样式 */
.category-card {
    text-decoration: none;
    color: inherit;
    display: block;
    transition: transform 0.2s;
}

.category-card:hover {
    transform: translateY(-5px);
}

.category-card .card {
    background: white;
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 1.5rem;
    height: 100%;
    transition: box-shadow 0.2s;
}

.category-card:hover .card {
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
}

.category-icon {
    font-size: 2rem;
    margin-bottom: 1rem;
    color: var(--primary-color);
}

.category-card .card-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-color);
}

.category-card .card-text {
    font-size: 0.9rem;
    color: #6c757d;
    margin-bottom: 0;
}

/* 热门课程卡片样式 */
.course-card {
    background: white;
    border: 1px solid var(--border-color);
    border-radius: 12px;
    overflow: hidden;
    transition: transform 0.2s, box-shadow 0.2s;
    height: 100%;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}

.course-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.15);
}

.course-card img {
    width: 100%;
    height: 160px;
    object-fit: cover;
}

.course-card .card-body {
    padding: 1.25rem;
    display: flex;
    flex-direction: column;
}

.course-card .course-category {
    font-size: 0.8rem;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.course-card .card-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-color);
}

.course-card .instructor {
    font-size: 0.9rem;
    color: #6c757d;
    margin-bottom: 0.5rem;
}

.course-card .course-stats {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.85rem;
    color: #6c757d;
    margin-top: auto;
}

.course-card .rating {
    color: #ffc107;
}

/* 响应式布局 */
.row {
    display: flex;
    flex-wrap: wrap;
    margin: -1rem;
}

[class^="col-"] {
    padding: 1rem;
}

.col-6 {
    width: 50%;
}

.col-12 {
    width: 100%;
}

@media (min-width: 768px) {
    .col-md-4 {
        width: 33.333333%;
    }
    
    .col-md-6 {
        width: 50%;
    }
}

@media (min-width: 992px) {
    .col-lg-3 {
        width: 25%;
    }
}

/* 暗色模式支持 */
@media (prefers-color-scheme: dark) {
    :root {
        color-scheme: dark;
    }

    body {
        background-color: var(--background-dark);
        color: white;
    }

    main {
        background-color: var(--background-dark);
    }

    .section-title {
        color: white;
    }

    .search-section input {
        background-color: #2d2d2d;
        border-color: rgba(255, 255, 255, 0.1);
        color: white;
    }

    .search-section input::placeholder {
        color: #adb5bd;
    }

    .search-section button {
        background-color: var(--primary-color);
    }

    .category-card .card,
    .course-card {
        background-color: #2d2d2d;
        border-color: rgba(255, 255, 255, 0.1);
        box-shadow: 0 2px 8px rgba(0, 0, 0, 0.2);
    }

    .category-card .card-title,
    .course-card .card-title {
        color: white;
    }

    .category-card .card-text,
    .course-card .instructor,
    .course-card .course-stats {
        color: #adb5bd;
    }

    .category-icon {
        color: var(--primary-color);
    }

    .course-card .course-category {
        color: var(--primary-color);
    }

    .course-card .rating {
        color: #ffd43b;
    }

    .category-card:hover .card,
    .course-card:hover {
        box-shadow: 0 8px 24px rgba(0, 0, 0, 0.3);
    }
}