[data-lang="zh"] { display: none; }

html.lang-zh [data-lang="en"] { display: none; }
html.lang-zh [data-lang="zh"] { display: revert; }

html.lang-zh .main-nav ul li[data-lang="en"] { display: none; }
html.lang-zh .main-nav ul li[data-lang="zh"] { display: inline-block; }

.main-nav ul li[data-lang="zh"] { display: none; }

body {
    margin: 0;
    padding: 0;
    
    /* 设置背景图片 */
    background-image: url('/image/bakcground.webp'), url('/image/background.jpg');
    background-size: cover;
    background-repeat: no-repeat;
    background-position: top center; 
    background-attachment: fixed;

    font-family: Arial, sans-serif;
    color: #e5e6e6;
}

.sticky-container {
    position: sticky; /* 粘性定位 */
    top: 0; /* 距离顶部0像素，滚动到顶部时固定 */
    z-index: 100; /* 确保在其他内容上方 */
}

.main-nav {
    position: fixed; /* 固定导航栏 */
    top: 0; /* 距离顶部0像素 */
    left: 0; /* 距离左边0像素 */
    right: 0; /* 距离右边0像素 */
    transition: top 0.3s; /* 平滑过渡效果 */
    z-index: 1000; /* 确保在其他内容上方 */
    width: 100%; /* 设置宽度为100% */
    text-align: center;
}

.main-nav ul {
    background-color: #17202b;
    list-style-type: none;
    padding: 0;
    margin: 0;
    height: 50px;
}

.main-nav ul li {
    display: inline-block;
    margin: 0 15px;
    line-height: 50px;
}

.main-nav ul li a {
    text-decoration: none;
    color: #e5e6e6;
    font-weight: bold;
    font-size: 18px;
    padding: 10px 15px;
    border-radius: 5px;
    transition: background-color 0.3s ease, color 0.3s ease;
}

.main-nav ul li a:hover {
    background-color: #b8ddec;
    color: #20201e;
}


.bottom {
    background-color: gainsboro;
}

/* 回到顶部按钮样式 */
.back-to-top {
    position: fixed;
    bottom: 40px;
    right: 40px;
    display: none;
    width: 60px;
    height: 60px;
    background-color: #17202b;
    color: #b8ddec;
    font-size: xx-large;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    z-index: 1000;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: background-color 0.3s ease;
}

.back-to-top:hover {
    background-color: #b8ddec;
    color: #20201e;
}