/* ============================================
   51视频 - 原创样式表
   配色方案：初音青(#00bcd4) / 电光蓝(#2979ff) / 星空紫(#7c4dff) / 樱花粉(#ff80ab)
   ============================================ */
*{margin:0;padding:0;box-sizing:border-box}
html{scroll-behavior:smooth;font-size:16px}
body{font-family:"PingFang SC","Hiragino Sans GB","Microsoft YaHei","Noto Sans SC",sans-serif;color:#2d3748;background:#f0fdfa;line-height:1.7}
a{color:#00897b;text-decoration:none;transition:color .3s}
a:hover{color:#7c4dff}
img{max-width:100%;height:auto;display:block}
.container{max-width:1200px;margin:0 auto;padding:0 20px}

/* 顶部导航 */
.site-header{background:linear-gradient(135deg,#004d40 0%,#00695c 50%,#00897b 100%);position:sticky;top:0;z-index:1000;box-shadow:0 2px 12px rgba(0,77,64,.3)}
.nav-wrap{display:flex;align-items:center;justify-content:space-between;padding:0 20px;max-width:1200px;margin:0 auto;height:64px}
.nav-logo{display:flex;align-items:center;gap:10px}
.nav-logo img{height:40px;width:40px;border-radius:8px}
.nav-logo span{color:#e0f2f1;font-size:1.3rem;font-weight:700;letter-spacing:1px}
.nav-menu{display:flex;list-style:none;gap:4px}
.nav-menu li a{color:#b2dfdb;padding:8px 14px;border-radius:6px;font-size:.9rem;transition:all .3s}
.nav-menu li a:hover,.nav-menu li a.active{color:#fff;background:rgba(255,255,255,.15)}
.nav-toggle{display:none;background:none;border:none;color:#e0f2f1;font-size:1.5rem;cursor:pointer}

/* 搜索框 */
.search-bar{background:#e0f2f1;padding:12px 0;border-bottom:1px solid #b2dfdb}
.search-wrap{max-width:600px;margin:0 auto;display:flex;gap:8px;padding:0 20px}
.search-wrap input{flex:1;padding:10px 16px;border:2px solid #80cbc4;border-radius:24px;font-size:.95rem;outline:none;transition:border-color .3s;background:#fff}
.search-wrap input:focus{border-color:#00bcd4}
.search-wrap button{padding:10px 24px;background:linear-gradient(135deg,#00bcd4,#2979ff);color:#fff;border:none;border-radius:24px;cursor:pointer;font-size:.95rem;transition:transform .2s}
.search-wrap button:hover{transform:scale(1.05)}

/* Hero区域 */
.hero-section{position:relative;height:520px;overflow:hidden;display:flex;align-items:center;justify-content:center}
.hero-bg{position:absolute;inset:0;background-size:cover;background-position:center;filter:brightness(.65)}
.hero-content{position:relative;z-index:2;text-align:center;color:#fff;padding:0 20px}
.hero-content h1{font-size:2.8rem;margin-bottom:16px;text-shadow:0 3px 20px rgba(0,188,212,.6)}
.hero-content p{font-size:1.15rem;max-width:680px;margin:0 auto 24px;opacity:.92;text-shadow:0 1px 8px rgba(0,0,0,.4)}
.hero-btn{display:inline-block;padding:14px 36px;background:linear-gradient(135deg,#00bcd4,#7c4dff);color:#fff;border-radius:30px;font-size:1.05rem;font-weight:600;transition:transform .3s,box-shadow .3s}
.hero-btn:hover{transform:translateY(-3px);box-shadow:0 8px 25px rgba(124,77,255,.4);color:#fff}

/* 通用板块 */
.section{padding:60px 0}
.section-alt{background:#e0f7fa}
.section-dark{background:linear-gradient(135deg,#004d40,#00695c);color:#e0f2f1}
.section-title{text-align:center;margin-bottom:40px}
.section-title h2{font-size:1.9rem;color:#004d40;margin-bottom:8px;position:relative;display:inline-block}
.section-dark .section-title h2{color:#e0f2f1}
.section-title h2::after{content:'';display:block;width:60px;height:3px;background:linear-gradient(90deg,#00bcd4,#7c4dff);margin:10px auto 0;border-radius:2px}
.section-title p{color:#546e7a;font-size:1rem}
.section-dark .section-title p{color:#b2dfdb}

/* 视频卡片网格 */
.video-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:24px}
.video-card{background:#fff;border-radius:12px;overflow:hidden;box-shadow:0 4px 16px rgba(0,77,64,.08);transition:transform .3s,box-shadow .3s}
.video-card:hover{transform:translateY(-6px);box-shadow:0 12px 32px rgba(0,77,64,.15)}
.video-thumb{position:relative;padding-top:56.25%;overflow:hidden;cursor:pointer}
.video-thumb img{position:absolute;inset:0;width:100%;height:100%;object-fit:cover;transition:transform .4s}
.video-card:hover .video-thumb img{transform:scale(1.08)}
.video-overlay{position:absolute;inset:0;display:flex;align-items:center;justify-content:center;background:rgba(0,77,64,.4);opacity:0;transition:opacity .3s}
.video-card:hover .video-overlay{opacity:1}
.play-btn{width:56px;height:56px;background:rgba(0,188,212,.9);border-radius:50%;display:flex;align-items:center;justify-content:center;transition:transform .3s}
.play-btn::after{content:'';border-style:solid;border-width:10px 0 10px 18px;border-color:transparent transparent transparent #fff;margin-left:3px}
.video-card:hover .play-btn{transform:scale(1.15)}
.video-info{padding:16px}
.video-info h3{font-size:1.05rem;color:#004d40;margin-bottom:6px;line-height:1.4}
.video-info p{font-size:.85rem;color:#78909c;margin-bottom:8px}
.video-tags{display:flex;flex-wrap:wrap;gap:6px}
.video-tags span{padding:3px 10px;background:#e0f7fa;color:#00897b;border-radius:12px;font-size:.75rem}
.video-meta{display:flex;gap:12px;margin-top:8px;font-size:.8rem;color:#90a4ae}

/* 分类模块 */
.category-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:20px}
.category-card{background:#fff;border-radius:12px;padding:28px 20px;text-align:center;box-shadow:0 4px 16px rgba(0,77,64,.06);transition:transform .3s,box-shadow .3s;border-top:3px solid transparent}
.category-card:hover{transform:translateY(-5px);box-shadow:0 8px 24px rgba(0,77,64,.12);border-top-color:#00bcd4}
.category-icon{font-size:2.2rem;margin-bottom:12px}
.category-card h3{font-size:1.05rem;color:#004d40;margin-bottom:8px}
.category-card p{font-size:.85rem;color:#78909c;line-height:1.5}

/* 社区模块 */
.community-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:20px}
.community-card{background:#fff;border-radius:12px;padding:24px;text-align:center;box-shadow:0 4px 12px rgba(0,77,64,.06);transition:all .3s}
.community-card:hover{transform:translateY(-4px);box-shadow:0 8px 20px rgba(0,77,64,.12)}
.community-card .icon{font-size:2rem;margin-bottom:10px}
.community-card h4{font-size:1rem;color:#004d40;margin-bottom:6px}
.community-card p{font-size:.83rem;color:#78909c}

/* 专家展示 */
.expert-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:24px}
.expert-card{background:#fff;border-radius:12px;overflow:hidden;box-shadow:0 4px 16px rgba(0,77,64,.08);text-align:center;transition:transform .3s}
.expert-card:hover{transform:translateY(-5px)}
.expert-card img{width:100%;height:220px;object-fit:cover}
.expert-card .info{padding:16px}
.expert-card h4{font-size:1.05rem;color:#004d40;margin-bottom:4px}
.expert-card .role{font-size:.85rem;color:#00897b;margin-bottom:8px}
.expert-card p{font-size:.82rem;color:#78909c;line-height:1.5}
.expert-card .btns{display:flex;gap:8px;justify-content:center;margin-top:12px}
.expert-card .btns a{padding:6px 14px;border-radius:20px;font-size:.8rem;transition:all .3s}
.btn-teal{background:#e0f7fa;color:#00897b}
.btn-teal:hover{background:#00bcd4;color:#fff}
.btn-purple{background:#ede7f6;color:#7c4dff}
.btn-purple:hover{background:#7c4dff;color:#fff}

/* 合作品牌 */
.partner-wall{display:flex;flex-wrap:wrap;gap:20px;justify-content:center;align-items:center}
.partner-wall .partner-item{background:#fff;padding:16px 28px;border-radius:10px;box-shadow:0 2px 8px rgba(0,77,64,.06);font-size:1rem;color:#546e7a;font-weight:600;transition:transform .3s}
.partner-wall .partner-item:hover{transform:scale(1.05)}

/* How-To */
.howto-steps{display:grid;grid-template-columns:repeat(4,1fr);gap:20px;counter-reset:step}
.howto-step{background:#fff;border-radius:12px;padding:28px 20px;text-align:center;box-shadow:0 4px 12px rgba(0,77,64,.06);position:relative;counter-increment:step}
.howto-step::before{content:counter(step);position:absolute;top:-14px;left:50%;transform:translateX(-50%);width:32px;height:32px;background:linear-gradient(135deg,#00bcd4,#7c4dff);color:#fff;border-radius:50%;display:flex;align-items:center;justify-content:center;font-weight:700;font-size:.9rem}
.howto-step h4{margin-top:10px;font-size:1rem;color:#004d40;margin-bottom:6px}
.howto-step p{font-size:.85rem;color:#78909c}

/* FAQ */
.faq-list{max-width:800px;margin:0 auto}
.faq-item{background:#fff;border-radius:10px;margin-bottom:12px;box-shadow:0 2px 8px rgba(0,77,64,.05);overflow:hidden}
.faq-q{padding:16px 20px;font-weight:600;color:#004d40;cursor:pointer;display:flex;justify-content:space-between;align-items:center;transition:background .3s}
.faq-q:hover{background:#e0f7fa}
.faq-q::after{content:'+';font-size:1.3rem;color:#00bcd4;transition:transform .3s}
.faq-item.open .faq-q::after{transform:rotate(45deg)}
.faq-a{padding:0 20px;max-height:0;overflow:hidden;transition:all .3s;color:#546e7a;font-size:.92rem;line-height:1.7}
.faq-item.open .faq-a{padding:0 20px 16px;max-height:300px}

/* 用户评价 */
.review-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:20px}
.review-card{background:#fff;border-radius:12px;padding:24px;box-shadow:0 4px 12px rgba(0,77,64,.06)}
.review-card .stars{color:#ffc107;font-size:1rem;margin-bottom:8px}
.review-card blockquote{font-size:.92rem;color:#546e7a;line-height:1.6;margin-bottom:10px;font-style:italic}
.review-card .author{font-size:.85rem;color:#00897b;font-weight:600}

/* 联系我们 */
.contact-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:30px;align-items:start}
.contact-info{background:#fff;border-radius:12px;padding:28px;box-shadow:0 4px 12px rgba(0,77,64,.06)}
.contact-info h3{color:#004d40;margin-bottom:16px;font-size:1.15rem}
.contact-info p{margin-bottom:10px;color:#546e7a;font-size:.92rem}
.contact-qr{display:flex;gap:20px;justify-content:center}
.contact-qr .qr-item{text-align:center}
.contact-qr .qr-item img{width:160px;height:160px;border-radius:8px;margin-bottom:8px}
.contact-qr .qr-item span{font-size:.85rem;color:#546e7a}

/* 社交分享 */
.share-btns{display:flex;gap:12px;justify-content:center;flex-wrap:wrap;margin-top:20px}
.share-btns a{padding:8px 20px;border-radius:20px;font-size:.85rem;color:#fff;transition:transform .2s}
.share-btns a:hover{transform:scale(1.08);color:#fff}
.share-wechat{background:#07c160}
.share-weibo{background:#e6162d}
.share-douyin{background:#161823}
.share-bilibili{background:#00a1d6}

/* 页脚 */
.site-footer{background:#004d40;color:#b2dfdb;padding:40px 0 20px}
.footer-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:30px;margin-bottom:30px}
.footer-col h4{color:#e0f2f1;font-size:1rem;margin-bottom:14px;position:relative;padding-bottom:8px}
.footer-col h4::after{content:'';position:absolute;bottom:0;left:0;width:30px;height:2px;background:#00bcd4}
.footer-col p,.footer-col a{font-size:.85rem;color:#80cbc4;display:block;margin-bottom:6px}
.footer-col a:hover{color:#e0f2f1}
.footer-col img{border-radius:6px;margin-top:8px}
.footer-bottom{text-align:center;padding-top:20px;border-top:1px solid rgba(255,255,255,.1);font-size:.83rem;color:#80cbc4}

/* EEAT声明 */
.eeat-notice{background:#e0f7fa;border-left:4px solid #00bcd4;padding:12px 16px;margin:20px 0;border-radius:0 8px 8px 0;font-size:.85rem;color:#004d40}

/* 面包屑 */
.breadcrumb{padding:10px 0;font-size:.85rem;color:#78909c}
.breadcrumb a{color:#00897b}
.breadcrumb span{margin:0 6px;color:#b0bec5}

/* 响应式 */
@media(max-width:1024px){
.video-grid,.category-grid,.expert-grid,.howto-steps{grid-template-columns:repeat(2,1fr)}
.community-grid{grid-template-columns:repeat(2,1fr)}
.footer-grid{grid-template-columns:repeat(2,1fr)}
}
@media(max-width:768px){
.nav-menu{display:none;position:absolute;top:64px;left:0;right:0;background:#004d40;flex-direction:column;padding:16px;gap:4px;box-shadow:0 4px 12px rgba(0,0,0,.2)}
.nav-menu.show{display:flex}
.nav-toggle{display:block}
.hero-section{height:380px}
.hero-content h1{font-size:1.8rem}
.video-grid{grid-template-columns:1fr}
.category-grid,.community-grid,.expert-grid,.howto-steps{grid-template-columns:1fr}
.review-grid,.contact-grid{grid-template-columns:1fr}
.footer-grid{grid-template-columns:1fr}
.search-wrap{flex-direction:column}
}