/* 基础样式 */
body {
    margin: 0;
    padding: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

/* 顶部样式 */
.site-header {
    background: #fff;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    padding: 1rem;
    position: relative;
}

.site-logo {
    max-width: 200px;
    height: auto;
}

/* 导航栏样式 */
.main-navigation {
    background: #f8f9fa;
    padding: 0.5rem 0;
}

/* 公告样式 */
.announcement {
    background: #fff8e1;
    padding: 1rem;
    margin: 1rem 0;
}

/* 容器 */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 15px;
}

/* 返回顶部按钮 */
.back-to-top {
    position: fixed;
    bottom: 20px;
    right: 20px;
    width: 40px;
    height: 40px;
    background-color: rgba(0,0,0,0.5);
    color: #fff;
    border-radius: 50%;
    text-align: center;
    line-height: 40px;
    z-index: 9999;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s, visibility 0.3s;
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
}

/* 页脚链接 */
.footer-links {
    padding: 20px 0;
    text-align: center;
}

.footer-links a {
    color: #555;
    text-decoration: none;
    margin: 0 10px;
    font-size: 14px;
    transition: color 0.3s;
    display: inline-block;
    padding: 5px;
}

.footer-links a:hover {
    color: #2271b1;
    text-decoration: underline;
}