body, html {
    margin: 0;
    padding: 0;
    font-family: Arial, sans-serif;
    height: 100%;
}

body {
    display: flex;
    flex-direction: column;
    background-size: cover;
    background-position: center;
    background-attachment: fixed;
}

header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background-color: rgba(255, 255, 255, 0.8);
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    z-index: 1000;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 8px 20px;
    max-width: 1200px;
    margin: 0 auto;
}

.site-name {
    font-size: 20px;
    font-weight: bold;
}

.header-links a {
    margin-left: 15px;
    text-decoration: none;
    color: #333;
    font-size: 14px;
}

.container {
    margin-top: 30px; /* 为固定的 header 留出空间 */
    display: flex;
    justify-content: center;
    padding: 20px;
}

main {
    background-color: rgba(255, 255, 255, 0.8);
    border-radius: 10px;
    padding: 20px;
    width: 90%;
    max-width: 1200px;
    min-height: 1000px; /* 设置一个较大的默认高度 */
    box-shadow: 0 0 10px rgba(0,0,0,0.1);
}

.promo-card {
    background-color: #fff;
    border-radius: 8px;
    padding: 15px;
    margin-bottom: 20px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    text-decoration: none;
    color: #333;
    display: flex;
    align-items: center;
    width: 100%;
    max-width: 300px;
}

.promo-card:hover {
    transform: translateY(-3px);
    box-shadow: 0 4px 8px rgba(0,0,0,0.15);
}

.promo-icon {
    font-size: 36px;
    margin-right: 15px;
}

.promo-content {
    flex-grow: 1;
}

.promo-title {
    font-size: 18px;
    font-weight: bold;
    margin-bottom: 3px;
}

.promo-description {
    font-size: 12px;
    color: #666;
}

.nav-container {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 15px;
    width: 100%;
}

.nav-item {
    background-color: #fff;
    border-radius: 6px;
    padding: 15px;
    text-align: center;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    transition: transform 0.3s ease;
}

.nav-item:hover {
    transform: translateY(-3px);
}

.nav-item a {
    text-decoration: none;
    color: #333;
    font-size: 16px;
    font-weight: bold;
}

@media (max-width: 768px) {
    .nav-container {
        grid-template-columns: repeat(3, 1fr);
    }
    
    .header-content {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .header-links {
        margin-top: 5px;
    }
    
    .header-links a {
        margin-left: 0;
        margin-right: 15px;
    }
}

@media (max-width: 480px) {
    .nav-container {
        grid-template-columns: repeat(2, 1fr);
    }
}