:root {
    --primary: #165DFF; /* 主色调 */
    --primary-light: #4080FF;
    --secondary: #6B7280; /* 辅助色 */
    --dark: #1F2937; /* 深色文本 */
    --light: #F9FAFB; /* 浅色背景 */
    --border: #E5E7EB; /* 边框色 */
    --shadow: 0 4px 20px rgba(0, 0, 0, 0.08); /* 统一阴影 */
    --radius: 8px; /* 统一圆角 */
    --transition: all 0.3s ease; /* 统一过渡效果 */
}

/* 全局样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

.container {
    max-width: 1200px; /* 限制最大宽度，避免大屏拉伸 */
    margin: 0 auto;
    padding: 0 20px;
}

section {
    padding: 60px 0; /* 增大区块间距，更显大气 */
}

body {
    font-family: 'Inter', 'Helvetica Neue', sans-serif; /* 现代无衬线字体 */
    font-size: 16px;
    color: var(--dark);
    line-height: 1.7;
    padding-top: 90px; /* 为固定头部预留空间 */
}

h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 20px;
    color: var(--dark);
}

h2 {
    font-size: 2rem;
    margin-bottom: 16px;
    position: relative;
    padding-bottom: 12px;
}

h2::after {
    content: '';
    position: absolute;
    left: 0;
    bottom: 0;
    width: 60px;
    height: 3px;
    background: var(--primary);
}

.text-gray {
    color: var(--secondary);
    font-size: 15px;
}

/* 头部样式 */
header.site-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: white;
    box-shadow: var(--shadow);
    z-index: 100; /* 避免被内容覆盖 */
    padding: 15px 0;
}

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

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

.site-logo {
    max-width: 100%;
    height: auto;
    transition: transform 0.3s ease;
}

.site-logo:hover {
    transform: scale(1.02);
}

/* 导航菜单样式 */
.main-nav ul {
    display: flex;
    list-style: none;
    gap: 30px; /* 增大导航项间距 */
    margin: 0;
    padding: 0;
}

.main-nav li {
    position: relative;
}

.main-nav a {
    font-size: 16px;
    color: var(--dark);
    padding: 8px 0;
    position: relative;
    text-decoration: none;
    transition: color 0.3s ease;
}

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

.main-nav a.active::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 2px;
    background: var(--primary);
}

/* 移动端菜单按钮 */
.mobile-menu-btn {
    display: none;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    width: 40px;
    height: 40px;
    background: none;
    border: none;
    cursor: pointer;
}

.mobile-menu-btn span {
    width: 25px;
    height: 3px;
    background-color: var(--dark);
    margin: 3px 0;
    transition: all 0.3s ease;
    border-radius: 3px;
}

/* 移动端菜单 */
.mobile-menu {
    display: none;
    background-color: white;
    border-top: 1px solid var(--border);
}

.mobile-menu ul {
    list-style: none;
    padding: 15px 0;
}

.mobile-menu li {
    text-align: center;
    margin-bottom: 10px;
}

.mobile-menu a {
    color: var(--dark);
    display: block;
    padding: 8px 0;
    text-decoration: none;
    transition: color 0.3s ease;
}

.mobile-menu a:hover,
.mobile-menu a.active {
    color: var(--primary);
}

/* 底部样式 */
footer.site-footer {
    background-color: var(--dark);
    color: white;
    padding: 60px 0 30px;
    margin-top: 60px;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 40px;
    margin-bottom: 40px;
}

.footer-section h3 {
    font-size: 1.3rem;
    margin-bottom: 20px;
    position: relative;
    padding-bottom: 10px;
    color: white;
}

.footer-section h3::after {
    content: '';
    position: absolute;
    left: 0;
    bottom: 0;
    width: 40px;
    height: 2px;
    background-color: var(--primary);
}

.footer-section p {
    margin-bottom: 15px;
    opacity: 0.9;
    line-height: 1.6;
}

.footer-section.links ul {
    list-style: none;
    margin: 0;
    padding: 0;
}

.footer-section.links li {
    margin-bottom: 10px;
}

.footer-section.links a {
    color: white;
    text-decoration: none;
    opacity: 0.9;
    transition: all 0.3s ease;
}

.footer-section.links a:hover {
    color: var(--primary);
    padding-left: 5px;
}

.copyright {
    padding-top: 30px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    text-align: center;
    font-size: 0.9rem;
    opacity: 0.8;
}

.copyright a {
    color: white;
    text-decoration: none;
    transition: color 0.3s ease;
}

.copyright a:hover {
    color: var(--primary);
    text-decoration: underline;
}

/* 组件样式 */
.card {
    background: white;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    overflow: hidden;
    transition: var(--transition);
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.12);
}

.card-content {
    padding: 24px; /* 增加内边距，更显宽松 */
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 10px 20px;
    border-radius: var(--radius);
    font-weight: 500;
    transition: var(--transition);
    border: none;
    cursor: pointer;
    text-decoration: none;
}

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

.btn-primary:hover {
    background: var(--primary-light);
}

.form-input {
    width: 100%;
    padding: 12px 16px;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    font-size: 16px;
    transition: var(--transition);
}

.form-input:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(22, 93, 255, 0.1);
    outline: none;
}

/* 响应式调整 */
@media (max-width: 768px) {
    h1 {
        font-size: 2rem;
    }
    
    h2 {
        font-size: 1.5rem;
    }
    
    .news-container {
        grid-template-columns: 1fr; /* 移动端单列布局 */
    }
    
    section {
        padding: 40px 0;
    }
    
    .main-nav {
        display: none;
    }
    
    .mobile-menu-btn {
        display: flex;
    }
    
    .mobile-menu.active {
        display: block;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .footer-section h3::after {
        left: 50%;
        transform: translateX(-50%);
    }
}
   
    /* 底部样式 */
    .site-footer {
        background-color: #333;
        color: #fff;
        padding: 40px 0 20px;
        margin-top: 50px;
    }
    
    .footer-content {
        display: flex;
        flex-wrap: wrap;
        justify-content: space-between;
        margin-bottom: 30px;
    }
    
    .footer-section {
        flex: 1;
        min-width: 250px;
        margin-bottom: 20px;
        padding: 0 15px;
    }
    
    .footer-section h3 {
        color: #fff;
        border-bottom: 2px solid #007bff;
        padding-bottom: 10px;
        margin-bottom: 15px;
    }
    
    .footer-section p {
        margin: 0 0 10px 0;
        line-height: 1.6;
    }
    
    .footer-section ul {
        list-style: none;
        padding: 0;
        margin: 0;
    }
    
    .footer-section li {
        margin-bottom: 8px;
    }
    
    .footer-section a {
        color: #ccc;
        text-decoration: none;
        transition: color 0.3s;
    }
    
    .footer-section a:hover {
        color: #007bff;
    }
    
    .copyright {
        text-align: center;
        padding-top: 20px;
        border-top: 1px solid #444;
        color: #aaa;
        font-size: 0.9rem;
    }