/* 额外样式增强 */
.card h1 { font-size: 1.8rem; color: #2c3e50; }
.video-card { transition: all 0.3s ease; }
.video-card:hover { box-shadow: 0 6px 20px rgba(0,0,0,0.2); }
footer { text-align: center; padding: 2rem; color: #999; font-size: 0.9rem; }