* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
html, body {
    margin: 0;
    padding: 0;
    height: 100%;
    width: 100%;
    overflow-x: hidden;
    font-family: "Noto Sans SC", Arial, sans-serif;
}
body {
    background-image: url("https://yuntt.60068006.xyz/robotstxt0830/skytop31a.jpg");
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    background-attachment: fixed;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}
.header {
    position: relative;
    width: 100%;
    padding: 20px;
}
.site-name {
    position: absolute;
    top: 0;
    left: 20px;
    font-size: 80px;
    font-weight: bold;
    color: black;
    text-shadow: 2px 2px 4px rgba(255, 255, 255, 0.5);
    z-index: 10;
}
.site-name a {
    text-decoration: none;
    color: black;
}
.subtitle {
    position: relative;
    display: inline-block;
    padding: 5px 15px;
    text-align: center;
    font-size: 20px;
    font-weight: bold;
    color: black;
    background-color: rgba(255, 255, 255, 0.8);
    margin-top: 80px;
    align-self: center;
    z-index: 0;
    border-radius: 5px;
}
.english-button {
    position: absolute;
    top: 10%;
    right: 20px;
}
.english-button a {
    display: inline-block;
    background-color: navy;
    color: white;
    padding: 10px 20px;
    font-size: 18px;
    font-weight: bold;
    text-decoration: none;
    border: 2px solid black;
    border-radius: 5px;
}
.navbar {
    margin-top: 20px;
    width: 100%;
    padding: 0 20px;
}
.navbar-content {
    display: flex;
    gap: 10px;
    padding: 0 20px;
}
.navbar-content ul {
    list-style: none;
    display: flex;
    gap: 10px;
    padding: 0;
    margin: 0;
}
.navbar-content li {
    display: inline-block;
}
.navbar-content a {
    display: inline-block;
    background-color: rgba(255, 255, 255, 0.5);
    padding: 15px 25px;
    font-size: 24px;
    font-weight: bold;
    color: black;
    text-decoration: none;
    border: 2px solid black;
    border-radius: 5px;
    transition: background-color 0.2s ease; /* 过渡动画，平滑变色 */
}

/* ========== 导航每个按钮独立底色 + hover加深 ========== */
.nav-item-1 { background-color: rgba(255, 220, 220, 0.8) !important; }
.nav-item-1:hover { background-color: rgba(255, 160, 160, 0.9) !important; }

.nav-item-2 { background-color: rgba(220, 255, 220, 0.8) !important; }
.nav-item-2:hover { background-color: rgba(160, 255, 160, 0.9) !important; }

.nav-item-3 { background-color: rgba(220, 220, 255, 0.8) !important; }
.nav-item-3:hover { background-color: rgba(160, 160, 255, 0.9) !important; }

.nav-item-4 { background-color: rgba(255, 255, 220, 0.8) !important; }
.nav-item-4:hover { background-color: rgba(255, 255, 120, 0.9) !important; }

.nav-item-5 { background-color: rgba(255, 220, 255, 0.8) !important; }
.nav-item-5:hover { background-color: rgba(255, 160, 255, 0.9) !important; }

.main-content {
    flex: 1;
    padding: 20px;
    max-width: 1200px;
    margin: 0 auto;
    width: 100%;
}
.title {
    text-align: center;
    font-size: 36px;
    font-weight: bold;
    margin: 30px 0;
    color: black;
    text-shadow: 2px 2px 4px rgba(255, 255, 255, 0.5);
}
.content {
    background-color: rgba(255, 255, 255, 0.8);
    padding: 30px;
    border-radius: 10px;
    margin-bottom: 20px;
}
.content p {
    font-size: 18px;
    line-height: 1.6;
    margin-bottom: 20px;
    color: black;
}
.article-list {
    margin: 30px 0;
    padding: 0 20px;
    list-style: none;
}
.article-list li {
    list-style: none;
    margin-bottom: 10px;
}
.article-list a {
    display: block;
    background-color: rgba(255, 255, 255, 0.8);
    color: black;
    padding: 10px 20px;
    font-size: 18px;
    font-weight: bold;
    text-decoration: none;
    border: 2px solid black;
    border-radius: 5px;
}
.nav-buttons {
    margin: 30px 0;
    padding: 0 20px;
}
.nav-buttons ul {
    list-style: none;
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}
.nav-buttons li {
    display: inline-block;
}
.nav-buttons a {
    display: inline-block;
    background-color: rgba(255, 255, 255, 0.8);
    color: black;
    padding: 10px 20px;
    font-size: 18px;
    font-weight: bold;
    text-decoration: none;
    border: 2px solid black;
    border-radius: 5px;
}
.nav-buttons .thisclass {
    display: inline-block;
    background-color: yellow;
    color: black;
    padding: 10px 20px;
    font-size: 18px;
    font-weight: bold;
    border: 2px solid black;
    border-radius: 5px;
}
.nav-buttons .pageinfo {
    display: inline-block;
    background-color: rgba(255, 255, 255, 0.8);
    color: black;
    padding: 10px 20px;
    font-size: 18px;
    font-weight: bold;
    border: 2px solid black;
    border-radius: 5px;
}
.footer {
    background-color: rgba(255, 255, 255, 0.8);
    padding: 30px;
    border-radius: 10px;
    text-align: center;
}
.copyright {
    font-size: 16px;
    font-weight: bold;
    color: black;
}
.two-columns {
    display: flex;
    gap: 20px;
    margin-top: 20px;
}
.section-a, .section-b {
    width: 50%;
    padding: 20px;
    background-color: rgba(255, 255, 255, 0.6);
    border-radius: 10px;
    border: 1px solid rgba(0, 0, 0, 0.1);
}
@media (max-width: 768px) {
    .site-name {
        font-size: 40px;
        top: 0;
        left: 10px;
    }
    .navbar {
        margin-top: 100px;
    }
    .title {
        font-size: 28px;
    }
    .content {
        padding: 20px;
    }
    .content p {
        font-size: 16px;
    }
}
@media (max-width: 480px) {
    .site-name {
        font-size: 30px;
    }
    .navbar {
        margin-top: 80px;
    }
    .navbar-content {
        font-size: 18px;
    }
    .title {
        font-size: 24px;
    }
    .two-columns {
        flex-direction: column;
    }
    .section-a, .section-b {
        width: 100%;
        margin-right: 0;
        margin-bottom: 20px;
    }
}