body {
    font-family: Arial, sans-serif;
    background-color: #f0f0f0;
    margin: 0;
    padding: 0;
}

header {
    background-color: #333;
    color: #fff;
    padding: 10px 0;
    text-align: center;
}

nav {
    background-color: #333;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1); /* 添加阴影提升导航栏的视觉效果 */
}

nav ul {
    list-style-type: none;
    padding: 0;
    margin: 0;
    display: flex;
    justify-content: center;
}

nav ul li {
    position: relative;
}

nav ul li a {
    display: block;
    padding: 15px 20px; /* 增加内边距以改善外观 */
    color: #fff;
    text-decoration: none;
    transition: background-color 0.3s; /* 添加过渡效果 */
}

nav ul li a:hover {
    background-color: #555;
}

nav ul li .dropdown-content {
    display: none;
    position: absolute;
    background-color: #f9f9f9;
    min-width: 160px;
    box-shadow: 0 8px 16px rgba(0, 0, 0, 0.2);
    z-index: 1;
}

nav ul li .dropdown-content li a {
    color: #333;
    padding: 12px 16px;
}

nav ul li .dropdown-content li a:hover {
    background-color: #ddd;
}

nav ul li:hover .dropdown-content {
    display: block;
}

main {
    padding: 20px;
    text-align: center;
}

h1 {
    margin-bottom: 20px;
}

footer {
    background-color: #333;
    color: #fff;
    text-align: center;
    padding: 10px 0;
    position: fixed;
    bottom: 0;
    width: 100%;
}