body {
    font-family: -apple-system, HuaweiSans, Helvetica Neue, Helvetica, Arial, PingFang SC, Hiragino Sans GB, STHeiti, Microsoft YaHei, Microsoft JhengHei, SimSun, sans-serif;
    font-size: 14px;
    line-height: 1.5;
    color: #575d6c;
    margin: 0;
    padding: 0;
    background-color: #f4f4f9;
    max-width: 1500px;
    margin: 0 auto;
}
header {
    background-color: #4CAF50;
    color: white;
    padding: 10px 0;
    text-align: center;
    border-radius: 15px 15px 0px 0px;
}
nav.top-nav {
    background-color: #333;
    color: white;
    padding: 10px 20px;
    text-align: center;
}
nav.top-nav a {
    color: white;
    margin: 0 15px;
    text-decoration: none;
}
nav.top-nav a.selected {
    color: #4CAF50; /* 选中状态的颜色 */
    font-weight: bold;
}
.container {
    display: flex;
    flex-wrap: wrap;
}
footer {
    background-color: #333;
    color: white;
    text-align: center;
    padding: 10px 0;
    width: 100%;
    border-radius: 0px 0px 15px 15px;
}
footer a {
    text-decoration: none;
    color: white;
    text-align: center;
    transition: background-color 0.3s; /* 平滑过渡 */
}
/* 响应式设计 */
@media (max-width: 600px) {
    header {
        padding: 5px 0;
    }
}