/* 响应式设计与移动端适配 */
.mobile-menu-btn {
    display: none;
    background: none;
    border: none;
    font-size: 24px;
    color: var(--primary-color);
    cursor: pointer;
}

.site-title-seo {
    font-size: 16px;
    color: var(--text-dark);
    margin-left: 15px;
    font-weight: 600;
    white-space: nowrap;
}

/* H5 视频卡片悬停播放按钮效果 */
.video-thumb {
    position: relative;
    overflow: hidden;
}

.video-thumb img {
    transition: transform 0.3s ease;
}

.video-card:hover .video-thumb img {
    transform: scale(1.05);
}

.video-thumb .play-icon {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 50px;
    height: 50px;
    background: rgba(0, 0, 0, 0.6);
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    opacity: 0;
    transition: opacity 0.3s ease;
    z-index: 10;
}

.video-thumb .play-icon::after {
    content: '';
    display: block;
    width: 0;
    height: 0;
    border-style: solid;
    border-width: 10px 0 10px 15px;
    border-color: transparent transparent transparent white;
    margin-left: 5px;
}

.video-card:hover .video-thumb .play-icon {
    opacity: 1;
}

@media (max-width: 992px) {
    .site-title-seo {
        display: none; /* 移动端空间有限，隐藏文字标题 */
    }
    
    .mobile-menu-btn {
        display: block;
    }
    
    #main-nav {
        display: none;
        position: absolute;
        top: 80px;
        left: 0;
        width: 100%;
        background: white;
        box-shadow: 0 5px 10px rgba(0,0,0,0.1);
        z-index: 1000;
    }
    
    .nav-menu {
        display: flex;
        flex-direction: column;
        padding: 0;
    }
    
    .nav-menu li {
        margin: 0;
        border-bottom: 1px solid var(--border-color);
    }
    
    .nav-menu li a {
        display: block;
        padding: 15px 20px;
    }
    
    .grid-4 {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    .grid-2, .grid-3, .grid-4, .footer-top {
        grid-template-columns: 1fr;
    }
    
    .hero {
        padding: 60px 0 !important;
    }
    
    .hero h2 {
        font-size: 32px !important;
    }
    
    .hero p {
        font-size: 16px !important;
    }
    
    .section-title h2 {
        font-size: 24px;
    }
    
    .video-card {
        margin-bottom: 20px;
    }
}