body {
    font-family: "Microsoft YaHei", sans-serif;
    background-color: #f5f5f5;
    color: #333;
    margin: 0;
    padding: 0;
}
header, footer {
    background-color: #fff;
    text-align: center;
    padding: 20px;
    border-bottom: 1px solid #ddd;
}
footer {
    margin-top: 50px;
    border-top: 1px solid #ddd;
    font-size: 14px;
}
main {
    max-width: 800px;
    margin: 40px auto;
    background: #fff;
    padding: 30px;
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
    line-height: 1.8;
}
nav a {
    text-decoration: none;
    margin: 0 10px;
    color: #2c3e50;
}
nav a:hover {
    text-decoration: underline;
}