* {margin:0;padding:0;box-sizing:border-box}
body {font-family:Arial,sans-serif;background:#f5f7fa;color:#333;line-height:1.7}
.container {max-width:1280px;margin:40px auto;padding:0 20px;display:flex;gap:30px;align-items:flex-start}
.main-column {flex:0 0 820px;display:flex;flex-direction:column;gap:25px}
.card {background:#fff;border-radius:16px;box-shadow:0 4px 20px rgba(0,0,0,0.08);padding:30px}
.title {font-size:26px;font-weight:700;margin-bottom:12px}
.meta {font-size:14px;color:#666;margin-bottom:25px}
.content {font-size:16px;line-height:1.8}
.content p {margin-bottom:15px;text-indent:2em}
.content img {max-width:100%;height:auto;border-radius:8px;margin:20px auto;display:block}
.right-sidebar {flex:1;min-width:280px;max-width:380px;display:flex;flex-direction:column;gap:25px}
.news-container,.related-section {background:#fff;border-radius:12px;padding:20px;box-shadow:0 2px 8px rgba(0,0,0,0.05)}
.news-container h2,.related-section h3 {font-size:20px;font-weight:600;color:#222;margin-bottom:15px;padding-bottom:10px;border-bottom:2px solid #eee}
/* 右侧：热门、最新资讯 统一单列 一行一个 */
.news-list,.related-list {display:grid;grid-template-columns:1fr;gap:10px;list-style:none;padding:0}
/* 左侧底部 最新课程、相关课程 强制双列 */
.main-column .related-list {grid-template-columns:1fr 1fr}
.news-list li,.related-list li {padding:10px 12px;border-radius:8px;background:#fff;transition:0.2s;overflow:hidden}
.news-list li:hover,.related-list li:hover {background:#f8faff}
.news-list a,.related-list a {display:flex;align-items:center;color:#333;text-decoration:none;max-width:100%;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;line-height:1.3}
.news-list a::before,.related-list a::before {content:'';width:6px;height:6px;background:#165DFF;border-radius:50%;margin-right:8px;flex-shrink:0}
.empty-tip {color:#999;padding:20px 0;text-align:center}
.error {max-width:600px;margin:80px auto;padding:40px;background:#fff;border-radius:12px;text-align:center}
.error h1 {color:#e74c3c}
@media(max-width:992px) {.container{display:block}.main-column{width:100%;margin-bottom:25px}.right-sidebar{max-width:100%;margin-top:25px}.main-column .related-list{grid-template-columns:1fr}}