/* 重置样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Microsoft YaHei', Arial, sans-serif;
    line-height: 1.6;
    color: #333;
}

.container {
    width: 90%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 15px;
}

/* 头部样式 */
header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 2rem 0;
    text-align: center;
}

header h1 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
}

header p {
    font-size: 1.2rem;
    opacity: 0.9;
}

/* 导航样式 */
nav {
    background: #fff;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    position: sticky;
    top: 0;
    z-index: 100;
}

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

nav ul li {
    margin: 0 1rem;
    position: relative;
}

nav ul li a {
    display: block;
    padding: 1rem 0;
    text-decoration: none;
    color: #333;
    font-weight: 500;
    transition: color 0.3s;
}

nav ul li a:hover {
    color: #667eea;
}

/* 下拉菜单样式 */
.dropdown {
    position: relative;
    display: inline-block;
}

.dropdown-content {
    display: none; /* 默认隐藏 */
    position: absolute;
    background-color: #fff;
    min-width: 250px;
    box-shadow: 0 8px 16px rgba(0,0,0,0.2);
    z-index: 1;
    top: 100%;
    left: 0;
    border-radius: 5px;
    max-height: 500px; /* 增加高度到500px */
    overflow-y: auto; /* 允许垂直滚动 */
}

/* 优化滚动条样式 */
.dropdown-content::-webkit-scrollbar {
    width: 8px;
}

.dropdown-content::-webkit-scrollbar-track {
    background: #f1f1f1;
    border-radius: 4px;
}

.dropdown-content::-webkit-scrollbar-thumb {
    background: #c1c1c1;
    border-radius: 4px;
}

.dropdown-content::-webkit-scrollbar-thumb:hover {
    background: #a8a8a8;
}

.dropdown-content a {
    color: #333;
    padding: 12px 16px;
    text-decoration: none;
    display: block;
    font-weight: normal;
    font-size: 0.9rem;
    border-bottom: 1px solid #eee;
}

.dropdown-content a:hover {
    background-color: #f8f9fa;
    color: #667eea;
}

/* 悬停显示下拉菜单 */
.dropdown:hover .dropdown-content {
    display: block;
}

.dropbtn {
    color: #333;
    padding: 1rem 0;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s;
    cursor: pointer;
}

.dropdown:hover .dropbtn {
    color: #667eea;
}

/* 主要内容样式 */
main {
    padding: 2rem 0;
}

.hero {
    text-align: center;
    padding: 3rem 0;
    background: #f8f9fa;
}

.hero h2 {
    font-size: 2rem;
    margin-bottom: 1rem;
    color: #333;
}

.hero p {
    font-size: 1.1rem;
    max-width: 700px;
    margin: 0 auto 2rem;
    color: #666;
}

.cta-buttons {
    display: flex;
    justify-content: center;
    gap: 1rem;
    flex-wrap: wrap;
}

.cta-center {
    text-align: center;
    margin-top: 2rem;
}

.btn {
    display: inline-block;
    padding: 1rem 2rem;
    border-radius: 50px;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s ease;
    font-size: 1rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    border: none;
    cursor: pointer;
    position: relative;
    overflow: hidden;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.2);
}

.btn.primary {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    box-shadow: 0 4px 15px rgba(102, 126, 234, 0.4);
}

.btn.primary:hover {
    background: linear-gradient(135deg, #764ba2 0%, #667eea 100%);
    transform: translateY(-3px) scale(1.05);
    box-shadow: 0 8px 20px rgba(102, 126, 234, 0.6);
}

.btn.secondary {
    background: transparent;
    color: #667eea;
    border: 2px solid #667eea;
    box-shadow: 0 4px 15px rgba(102, 126, 234, 0.2);
}

.btn.secondary:hover {
    background: rgba(102, 126, 234, 0.1);
    color: #764ba2;
    transform: translateY(-3px) scale(1.05);
    box-shadow: 0 8px 20px rgba(102, 126, 234, 0.3);
    border-color: #764ba2;
}

.content-section {
    padding: 3rem 0;
}

.content-section h2 {
    text-align: center;
    font-size: 2rem;
    margin-bottom: 2rem;
    color: #333;
}

.knowledge-map {
    text-align: center;
    margin: 2rem 0;
}

.knowledge-map img {
    max-width: 100%;
    height: auto;
    border-radius: 8px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.content-section {
    scroll-margin-top: 80px;
}

.feature-card {
    background: white;
    border-radius: 8px;
    padding: 2rem;
    box-shadow: 0 5px 15px rgba(0,0,0,0.05);
    transition: transform 0.3s, box-shadow 0.3s, opacity 0.3s;
    text-align: center;
    opacity: 0;
    transform: translateY(20px);
}

.feature-card.animate-in {
    opacity: 1;
    transform: translateY(0);
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 25px rgba(0,0,0,0.1);
}

.feature-card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: #667eea;
}

.feature-card p {
    color: #666;
}

/* 页脚样式 */
footer {
    background: #333;
    color: white;
    text-align: center;
    padding: 1.5rem 0;
    margin-top: 2rem;
}

/* 动画关键帧 */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* 响应式设计 */
@media (max-width: 768px) {
    header h1 {
        font-size: 2rem;
    }
    
    nav ul {
        flex-direction: column;
        align-items: center;
    }
    
    nav ul li {
        margin: 0.2rem 0;
    }
    
    .hero {
        padding: 2rem 0;
    }
    
    .hero h2 {
        font-size: 1.5rem;
    }
    
    .content-section h2 {
        font-size: 1.5rem;
    }
    
    .cta-buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .btn {
        width: 80%;
        text-align: center;
    }
    
    /* 移动端下拉菜单 */
    .dropdown-content {
        position: static;
        display: none;
        width: 100%;
        max-height: 300px;
    }
    
    .dropdown:hover .dropdown-content {
        display: none;
    }
    
    .dropdown.active .dropdown-content {
        display: block;
    }
}