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

body {
    font-family: 'Microsoft YaHei', 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #f7f9fc;
}

.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* 链接样式 */
a {
    text-decoration: none;
    color: #0071e3;
    transition: all 0.3s ease;
}

a:hover {
    color: #0353a4;
}

/* 按钮样式 */
.btn {
    display: inline-block;
    padding: 12px 24px;
    border-radius: 30px;
    font-weight: 500;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
}

.primary-btn {
    background-color: #0071e3;
    color: white;
    border: 2px solid #0071e3;
    box-shadow: 0 4px 12px rgba(0, 113, 227, 0.3);
}

.primary-btn:hover {
    background-color: #0353a4;
    border-color: #0353a4;
    color: white;
    transform: translateY(-2px);
    box-shadow: 0 6px 15px rgba(0, 113, 227, 0.4);
}

/* 头部样式 */
header {
    background: linear-gradient(135deg, #4fa474 0%, #2aafdb 100%);
    color: white;
    padding: 20px 0;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.header-content {
    display: flex;
    align-items: center;
    justify-content: center;
    flex-wrap: wrap;
    text-align: center;
    padding: 0 20px;
}

.logo {
    height: 80px;
    margin-right: 20px;
}

.header-text h1 {
    font-size: 2rem;
    margin-bottom: 5px;
}

.header-text p {
    font-size: 1.1rem;
    opacity: 0.9;
}

/* 导航栏样式 */
.main-nav {
    background-color: rgba(255, 255, 255, 0.95);
    padding: 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

.main-nav ul {
    display: flex;
    list-style: none;
    justify-content: center;
    flex-wrap: wrap;
}

.main-nav li {
    flex: 1;
    text-align: center;
    max-width: 170px;
}

.main-nav a {
    display: block;
    color: #333;
    padding: 15px 12px;
    font-weight: 500;
    transition: all 0.3s ease;
    position: relative;
    font-size: 0.95rem;
}

.main-nav a:hover {
    background-color: rgba(0, 113, 227, 0.05);
    color: #0071e3;
}

.main-nav a.active {
    color: #0071e3;
    font-weight: 600;
}

.main-nav a.active:after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 3px;
    background-color: #0071e3;
}

/* 英雄区域样式 */
.hero {
    background: linear-gradient(135deg, rgba(42, 175, 219, 0.9) 0%, rgba(79, 164, 116, 0.9) 100%), url('../MainWebsite/images/hero-bg.jpg');
    background-size: cover;
    background-position: center;
    color: white;
    padding: 80px 0;
    text-align: center;
    position: relative;
}

.hero h2 {
    font-size: 2.5rem;
    margin-bottom: 20px;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
}

.hero p {
    font-size: 1.2rem;
    max-width: 700px;
    margin: 0 auto;
    line-height: 1.7;
    text-shadow: 0 1px 2px rgba(0, 0, 0, 0.2);
}

/* 视频类别部分 */
.video-category {
    padding: 60px 0;
}

.video-category:nth-child(odd) {
    background-color: #f5f9ff;
}

.section-title {
    text-align: center;
    margin-bottom: 40px;
    color: #0071e3;
    font-size: 2rem;
    position: relative;
    padding-bottom: 15px;
    font-weight: 700;
}

.section-title:after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 80px;
    height: 3px;
    background: linear-gradient(90deg, #0071e3, #4fa474);
    border-radius: 2px;
}

.video-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: 30px;
    margin-bottom: 40px;
}

.video-card {
    background-color: white;
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.08);
    transition: all 0.3s ease;
    height: 100%;
    display: flex;
    flex-direction: column;
}

.video-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 12px 20px rgba(0, 113, 227, 0.15);
}

.video-thumbnail {
    position: relative;
    overflow: hidden;
    height: 200px;
}

.video-thumbnail img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.5s ease;
}

.video-card:hover .video-thumbnail img {
    transform: scale(1.05);
}

.play-btn {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 60px;
    height: 60px;
    background-color: rgba(0, 113, 227, 0.8);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 24px;
    opacity: 0.9;
    transition: all 0.3s ease;
    cursor: pointer;
}

.video-card:hover .play-btn {
    background-color: #0071e3;
    transform: translate(-50%, -50%) scale(1.1);
}

.video-info {
    padding: 20px;
    flex: 1;
    display: flex;
    flex-direction: column;
}

.video-info h3 {
    font-size: 18px;
    margin-bottom: 10px;
    color: #0071e3;
    line-height: 1.4;
}

.video-info p {
    color: #555;
    font-size: 14px;
    line-height: 1.5;
    margin-bottom: 15px;
    flex: 1;
}

.video-meta {
    display: flex;
    justify-content: space-between;
    margin-bottom: 15px;
    font-size: 13px;
    color: #666;
}

.duration {
    display: flex;
    align-items: center;
}

.duration:before {
    content: '⏱️';
    margin-right: 5px;
}

.level {
    display: flex;
    align-items: center;
}

.level:before {
    content: '📊';
    margin-right: 5px;
}

.watch-btn {
    display: inline-block;
    padding: 8px 16px;
    background-color: #0071e3;
    color: white;
    border-radius: 4px;
    font-size: 14px;
    transition: all 0.3s ease;
    text-align: center;
}

.watch-btn:hover {
    background-color: #0353a4;
    color: white;
}

.more-videos {
    text-align: center;
    margin-top: 20px;
}

.more-btn {
    display: inline-block;
    padding: 8px 20px;
    color: #0071e3;
    border: 1px solid #0071e3;
    border-radius: 30px;
    font-size: 14px;
    transition: all 0.3s ease;
}

.more-btn:hover {
    background-color: #0071e3;
    color: white;
}

/* 页脚样式 */
footer {
    background-color: #1a2a3a;
    color: white;
    padding: 50px 0 20px;
}

.footer-content {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    margin-bottom: 40px;
}

.footer-logo {
    margin-bottom: 30px;
    flex: 1;
    min-width: 250px;
}

.footer-logo h3 {
    color: white;
    margin-bottom: 15px;
}

.footer-links {
    display: flex;
    flex-wrap: wrap;
    flex: 2;
    justify-content: space-around;
}

.footer-links-group {
    margin-bottom: 20px;
    min-width: 150px;
}

.footer-links-group h4 {
    color: white;
    margin-bottom: 15px;
}

.footer-links-group ul {
    list-style: none;
}

.footer-links-group li {
    margin-bottom: 8px;
}

.footer-links-group a {
    color: rgba(255, 255, 255, 0.7);
}

.footer-links-group a:hover {
    color: white;
}

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

.footer-bottom p {
    color: rgba(255, 255, 255, 0.5);
    font-size: 14px;
}

/* 响应式设计 */
@media screen and (max-width: 768px) {
    .header-content {
        flex-direction: column;
    }
    
    .logo {
        margin-right: 0;
        margin-bottom: 15px;
    }
    
    .video-grid {
        grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    }
    
    .hero h2 {
        font-size: 2rem;
    }
    
    .hero p {
        font-size: 1rem;
    }
    
    .footer-content {
        flex-direction: column;
    }
}

@media screen and (max-width: 480px) {
    .video-grid {
        grid-template-columns: 1fr;
    }
    
    .video-thumbnail {
        height: 180px;
    }
}