/* ============================================
   51视频 - 原创CSS样式表
   配色：赛博紫#6C5CE7 + 荧光青#00D2D3 + 樱花粉#FD79A8
   布局：粘性导航 + 瀑布流 + 横向滚动 + 左右交替
   ============================================ */

/* === 基础重置 === */
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth;font-size:16px}
body{font-family:'PingFang SC','Microsoft YaHei','Hiragino Sans GB',sans-serif;background:#0D0B1E;color:#F0EDFF;line-height:1.7;overflow-x:hidden}
a{color:#00D2D3;text-decoration:none;transition:color .3s}
a:hover{color:#FD79A8}
img{max-width:100%;height:auto;display:block}
ul,ol{list-style:none}
h1,h2,h3,h4,h5,h6{font-weight:700;line-height:1.3}

/* === 容器 === */
.sv-wrap{max-width:1200px;margin:0 auto;padding:0 20px}

/* === 粘性导航 === */
.sv-header{position:sticky;top:0;z-index:1000;background:rgba(13,11,30,.92);backdrop-filter:blur(12px);border-bottom:1px solid rgba(108,92,231,.3);padding:0 24px}
.sv-header-inner{display:flex;align-items:center;justify-content:space-between;max-width:1200px;margin:0 auto;height:64px}
.sv-logo{display:flex;align-items:center;gap:10px}
.sv-logo img{height:40px;width:auto}
.sv-logo span{font-size:1.3rem;font-weight:800;background:linear-gradient(135deg,#6C5CE7,#00D2D3);-webkit-background-clip:text;-webkit-text-fill-color:transparent}
.sv-search{flex:0 0 280px;position:relative}
.sv-search input{width:100%;padding:8px 36px 8px 14px;border-radius:20px;border:1px solid rgba(108,92,231,.4);background:rgba(26,23,51,.8);color:#F0EDFF;font-size:.9rem;outline:none;transition:border-color .3s}
.sv-search input:focus{border-color:#00D2D3}
.sv-search button{position:absolute;right:4px;top:50%;transform:translateY(-50%);background:linear-gradient(135deg,#6C5CE7,#00D2D3);border:none;color:#fff;width:28px;height:28px;border-radius:50%;cursor:pointer;font-size:.8rem;display:flex;align-items:center;justify-content:center}
.sv-nav{display:flex;gap:24px;align-items:center}
.sv-nav a{color:#A29BCC;font-size:.95rem;font-weight:500;padding:4px 0;position:relative;transition:color .3s}
.sv-nav a::after{content:'';position:absolute;bottom:-2px;left:0;width:0;height:2px;background:linear-gradient(90deg,#6C5CE7,#00D2D3);transition:width .3s}
.sv-nav a:hover,
.sv-nav a.active{color:#F0EDFF}
.sv-nav a:hover::after,
.sv-nav a.active::after{width:100%}

/* 移动端菜单 */
.sv-menu-btn{display:none;background:none;border:none;color:#F0EDFF;font-size:1.5rem;cursor:pointer}

/* === Banner 视差 === */
.sv-banner{position:relative;height:520px;overflow:hidden;display:flex;align-items:center;justify-content:center}
.sv-banner-bg{position:absolute;inset:0;background-size:cover;background-position:center;background-attachment:fixed;filter:brightness(.55)}
.sv-banner-overlay{position:absolute;inset:0;background:linear-gradient(180deg,rgba(13,11,30,.3) 0%,rgba(13,11,30,.85) 100%)}
.sv-banner-content{position:relative;z-index:2;text-align:center;max-width:700px;padding:0 20px}
.sv-banner-content h1{font-size:2.8rem;margin-bottom:16px;background:linear-gradient(135deg,#fff,#00D2D3);-webkit-background-clip:text;-webkit-text-fill-color:transparent}
.sv-banner-content p{font-size:1.15rem;color:#A29BCC;margin-bottom:24px}
.sv-banner-content .sv-btn{display:inline-block;padding:12px 32px;border-radius:28px;background:linear-gradient(135deg,#6C5CE7,#00D2D3);color:#fff;font-weight:600;font-size:1rem;transition:transform .3s,box-shadow .3s}
.sv-banner-content .sv-btn:hover{transform:translateY(-2px);box-shadow:0 8px 24px rgba(108,92,231,.4)}

/* === 面包屑 === */
.sv-breadcrumb{padding:14px 0;font-size:.85rem;color:#A29BCC}
.sv-breadcrumb a{color:#6C5CE7}
.sv-breadcrumb span{margin:0 6px;color:#555}

/* === 通用标题 === */
.sv-section{padding:60px 0}
.sv-section-title{text-align:center;margin-bottom:40px}
.sv-section-title h2{font-size:2rem;margin-bottom:8px;position:relative;display:inline-block}
.sv-section-title h2::after{content:'';display:block;width:60px;height:3px;background:linear-gradient(90deg,#6C5CE7,#00D2D3);margin:10px auto 0}
.sv-section-title p{color:#A29BCC;font-size:.95rem;margin-top:8px}

/* === 影视传媒 - 瀑布流卡片 === */
.sv-waterfall{column-count:3;column-gap:20px}
.sv-card{break-inside:avoid;margin-bottom:20px;background:#1A1733;border-radius:12px;overflow:hidden;border:1px solid rgba(108,92,231,.15);transition:transform .3s,box-shadow .3s}
.sv-card:hover{transform:translateY(-6px);box-shadow:0 12px 32px rgba(108,92,231,.25)}
.sv-card-thumb{position:relative;overflow:hidden;cursor:pointer}
.sv-card-thumb img{width:100%;transition:transform .4s}
.sv-card:hover .sv-card-thumb img{transform:scale(1.05)}
.sv-card-play{position:absolute;inset:0;display:flex;align-items:center;justify-content:center;background:rgba(13,11,30,.5);opacity:0;transition:opacity .3s}
.sv-card-thumb:hover .sv-card-play{opacity:1}
.sv-card-play i{width:56px;height:56px;background:rgba(108,92,231,.85);border-radius:50%;display:flex;align-items:center;justify-content:center;font-size:1.5rem;color:#fff;backdrop-filter:blur(4px)}
.sv-card-play i::after{content:'';display:block;width:0;height:0;border-style:solid;border-width:10px 0 10px 18px;border-color:transparent transparent transparent #fff;margin-left:4px}
.sv-card-info{padding:16px}
.sv-card-info h3{font-size:1.05rem;margin-bottom:6px;color:#F0EDFF}
.sv-card-info p{font-size:.85rem;color:#A29BCC;line-height:1.5}
.sv-card-meta{display:flex;gap:12px;margin-top:10px;font-size:.78rem;color:#6C5CE7}
.sv-card-meta span{display:flex;align-items:center;gap:4px}
.sv-card-tags{display:flex;flex-wrap:wrap;gap:6px;margin-top:10px}
.sv-card-tags span{padding:2px 10px;border-radius:12px;background:rgba(108,92,231,.15);color:#00D2D3;font-size:.75rem}

/* === 娱乐专区 - 横向滚动 === */
.sv-hscroll-wrap{overflow-x:auto;padding-bottom:16px;-webkit-overflow-scrolling:touch}
.sv-hscroll-wrap::-webkit-scrollbar{height:6px}
.sv-hscroll-wrap::-webkit-scrollbar-track{background:rgba(26,23,51,.5);border-radius:3px}
.sv-hscroll-wrap::-webkit-scrollbar-thumb{background:linear-gradient(90deg,#6C5CE7,#00D2D3);border-radius:3px}
.sv-hscroll{display:flex;gap:20px;min-width:max-content}
.sv-hscroll .sv-card{flex:0 0 260px;margin-bottom:0}

/* === AI赋能 - 左右交替 === */
.sv-alternate{display:flex;align-items:center;gap:40px;margin-bottom:48px}
.sv-alternate:nth-child(even){flex-direction:row-reverse}
.sv-alternate-img{flex:0 0 45%;border-radius:12px;overflow:hidden}
.sv-alternate-img img{width:100%;border-radius:12px;transition:transform .4s}
.sv-alternate-img:hover img{transform:scale(1.03)}
.sv-alternate-text{flex:1}
.sv-alternate-text h3{font-size:1.4rem;margin-bottom:12px;color:#00D2D3}
.sv-alternate-text p{color:#A29BCC;margin-bottom:12px;font-size:.95rem}
.sv-alternate-text .sv-btn-sm{display:inline-block;padding:8px 20px;border-radius:20px;border:1px solid #6C5CE7;color:#6C5CE7;font-size:.85rem;transition:all .3s}
.sv-alternate-text .sv-btn-sm:hover{background:#6C5CE7;color:#fff}

/* === 社区 - 六宫格 === */
.sv-grid6{display:grid;grid-template-columns:repeat(3,1fr);gap:20px}
.sv-grid6-item{background:#1A1733;border-radius:12px;padding:28px 20px;text-align:center;border:1px solid rgba(108,92,231,.15);transition:all .3s}
.sv-grid6-item:hover{border-color:#00D2D3;transform:translateY(-4px);box-shadow:0 8px 24px rgba(0,210,211,.15)}
.sv-grid6-item .sv-icon{width:52px;height:52px;margin:0 auto 14px;background:linear-gradient(135deg,#6C5CE7,#00D2D3);border-radius:14px;display:flex;align-items:center;justify-content:center;font-size:1.5rem;color:#fff}
.sv-grid6-item h4{font-size:1.05rem;margin-bottom:8px;color:#F0EDFF}
.sv-grid6-item p{font-size:.85rem;color:#A29BCC}

/* === 专家 - 圆形头像悬浮卡片 === */
.sv-experts{display:grid;grid-template-columns:repeat(4,1fr);gap:24px}
.sv-expert-card{background:#1A1733;border-radius:16px;padding:28px 20px;text-align:center;border:1px solid rgba(108,92,231,.15);transition:all .3s;position:relative;overflow:hidden}
.sv-expert-card::before{content:'';position:absolute;top:0;left:0;right:0;height:80px;background:linear-gradient(135deg,#6C5CE7,#00D2D3);opacity:.15}
.sv-expert-card:hover{transform:translateY(-6px);box-shadow:0 12px 32px rgba(108,92,231,.2)}
.sv-expert-card img{width:88px;height:88px;border-radius:50%;object-fit:cover;border:3px solid #6C5CE7;margin:0 auto 14px;position:relative;z-index:1}
.sv-expert-card h4{font-size:1rem;margin-bottom:4px;color:#F0EDFF}
.sv-expert-card .sv-role{font-size:.82rem;color:#00D2D3;margin-bottom:8px}
.sv-expert-card p{font-size:.82rem;color:#A29BCC;line-height:1.5}
.sv-expert-card .sv-expert-btns{display:flex;gap:8px;justify-content:center;margin-top:12px}
.sv-expert-card .sv-expert-btns a{padding:5px 14px;border-radius:16px;font-size:.78rem;border:1px solid #6C5CE7;color:#6C5CE7;transition:all .3s}
.sv-expert-card .sv-expert-btns a:hover{background:#6C5CE7;color:#fff}

/* === FAQ 手风琴 === */
.sv-faq-list{max-width:800px;margin:0 auto}
.sv-faq-item{background:#1A1733;border-radius:10px;margin-bottom:12px;border:1px solid rgba(108,92,231,.15);overflow:hidden}
.sv-faq-q{padding:16px 20px;cursor:pointer;display:flex;justify-content:space-between;align-items:center;font-weight:600;color:#F0EDFF;transition:background .3s}
.sv-faq-q:hover{background:rgba(108,92,231,.1)}
.sv-faq-q .sv-arrow{transition:transform .3s;color:#6C5CE7;font-size:1.2rem}
.sv-faq-item.active .sv-faq-q .sv-arrow{transform:rotate(180deg)}
.sv-faq-a{max-height:0;overflow:hidden;transition:max-height .4s ease;padding:0 20px}
.sv-faq-item.active .sv-faq-a{max-height:300px;padding:0 20px 16px}
.sv-faq-a p{color:#A29BCC;font-size:.9rem;line-height:1.7}

/* === 用户评论 - 卡片轮播 === */
.sv-reviews-track{display:flex;gap:20px;overflow:hidden;position:relative}
.sv-review-card{flex:0 0 calc(33.333% - 14px);background:#1A1733;border-radius:12px;padding:24px;border:1px solid rgba(108,92,231,.15)}
.sv-review-card .sv-stars{color:#FD79A8;margin-bottom:10px;font-size:.9rem;letter-spacing:2px}
.sv-review-card p{font-size:.9rem;color:#A29BCC;line-height:1.6;margin-bottom:12px;font-style:italic}
.sv-review-card .sv-reviewer{display:flex;align-items:center;gap:10px}
.sv-review-card .sv-reviewer-avatar{width:36px;height:36px;border-radius:50%;background:linear-gradient(135deg,#6C5CE7,#00D2D3);display:flex;align-items:center;justify-content:center;color:#fff;font-weight:700;font-size:.85rem}
.sv-review-card .sv-reviewer-name{font-size:.85rem;color:#F0EDFF}
.sv-review-card .sv-reviewer-date{font-size:.75rem;color:#A29BCC}

/* === 合作品牌 Logo墙 === */
.sv-partners{display:flex;flex-wrap:wrap;justify-content:center;gap:32px;padding:20px 0}
.sv-partners img{height:40px;opacity:.5;filter:grayscale(1);transition:all .3s}
.sv-partners img:hover{opacity:1;filter:grayscale(0)}

/* === How-To 指南 === */
.sv-howto{display:grid;grid-template-columns:repeat(4,1fr);gap:20px;counter-reset:step}
.sv-howto-step{background:#1A1733;border-radius:12px;padding:24px 20px;text-align:center;border:1px solid rgba(108,92,231,.15);position:relative;counter-increment:step}
.sv-howto-step::before{content:counter(step);display:block;width:40px;height:40px;line-height:40px;border-radius:50%;background:linear-gradient(135deg,#6C5CE7,#00D2D3);color:#fff;font-weight:700;font-size:1.1rem;margin:0 auto 12px;text-align:center}
.sv-howto-step h4{font-size:.95rem;margin-bottom:6px;color:#F0EDFF}
.sv-howto-step p{font-size:.82rem;color:#A29BCC}

/* === 联系我们 === */
.sv-contact-grid{display:grid;grid-template-columns:1fr 1fr;gap:32px}
.sv-contact-info{background:#1A1733;border-radius:12px;padding:32px;border:1px solid rgba(108,92,231,.15)}
.sv-contact-info h3{font-size:1.3rem;margin-bottom:16px;color:#00D2D3}
.sv-contact-info p{margin-bottom:10px;color:#A29BCC;font-size:.9rem}
.sv-contact-info strong{color:#F0EDFF}
.sv-contact-qr{display:flex;gap:24px;justify-content:center;align-items:flex-start}
.sv-contact-qr div{text-align:center}
.sv-contact-qr img{width:140px;height:140px;border-radius:8px;border:2px solid rgba(108,92,231,.3)}
.sv-contact-qr p{font-size:.82rem;color:#A29BCC;margin-top:8px}

/* === 社交分享 === */
.sv-share{display:flex;gap:12px;justify-content:center;padding:20px 0}
.sv-share a{width:40px;height:40px;border-radius:50%;background:#1A1733;border:1px solid rgba(108,92,231,.3);display:flex;align-items:center;justify-content:center;color:#A29BCC;font-size:.9rem;transition:all .3s}
.sv-share a:hover{background:#6C5CE7;color:#fff;border-color:#6C5CE7}

/* === 页脚 === */
.sv-footer{background:#0A0820;border-top:1px solid rgba(108,92,231,.2);padding:48px 0 24px}
.sv-footer-grid{display:grid;grid-template-columns:2fr 1fr 1fr 1fr;gap:32px;margin-bottom:32px}
.sv-footer-col h4{font-size:1rem;margin-bottom:14px;color:#F0EDFF;position:relative;padding-bottom:8px}
.sv-footer-col h4::after{content:'';position:absolute;bottom:0;left:0;width:30px;height:2px;background:linear-gradient(90deg,#6C5CE7,#00D2D3)}
.sv-footer-col p{font-size:.85rem;color:#A29BCC;line-height:1.7;margin-bottom:8px}
.sv-footer-col a{display:block;font-size:.85rem;color:#A29BCC;margin-bottom:6px;transition:color .3s}
.sv-footer-col a:hover{color:#00D2D3}
.sv-footer-col .sv-footer-logo{display:flex;align-items:center;gap:8px;margin-bottom:12px}
.sv-footer-col .sv-footer-logo img{height:32px}
.sv-footer-col .sv-footer-logo span{font-size:1.1rem;font-weight:700;background:linear-gradient(135deg,#6C5CE7,#00D2D3);-webkit-background-clip:text;-webkit-text-fill-color:transparent}
.sv-footer-bottom{text-align:center;padding-top:20px;border-top:1px solid rgba(108,92,231,.15);font-size:.82rem;color:#A29BCC}
.sv-footer-bottom a{color:#6C5CE7}

/* === 返回顶部 === */
.sv-backtop{position:fixed;bottom:32px;right:32px;width:44px;height:44px;border-radius:50%;background:linear-gradient(135deg,#6C5CE7,#00D2D3);color:#fff;border:none;cursor:pointer;font-size:1.2rem;display:none;align-items:center;justify-content:center;z-index:999;box-shadow:0 4px 16px rgba(108,92,231,.4);transition:transform .3s}
.sv-backtop:hover{transform:translateY(-3px)}
.sv-backtop.show{display:flex}

/* === 内页通用 === */
.sv-page-header{background:linear-gradient(135deg,rgba(108,92,231,.15),rgba(0,210,211,.1));padding:48px 0 32px;text-align:center}
.sv-page-header h1{font-size:2rem;margin-bottom:8px}
.sv-page-header p{color:#A29BCC;font-size:.95rem}

/* 内页内容区 */
.sv-content{padding:40px 0}
.sv-content h2{font-size:1.5rem;margin:24px 0 12px;color:#00D2D3}
.sv-content h3{font-size:1.2rem;margin:20px 0 10px;color:#F0EDFF}
.sv-content p{margin-bottom:14px;color:#A29BCC;font-size:.95rem}
.sv-content .sv-author-line{font-size:.82rem;color:#6C5CE7;margin-bottom:20px}

/* 视频播放器卡片 */
.sv-player-wrap{position:relative;background:#000;border-radius:12px;overflow:hidden;aspect-ratio:16/9;margin:20px 0}
.sv-player-wrap img{width:100%;height:100%;object-fit:cover}
.sv-player-wrap .sv-play-overlay{position:absolute;inset:0;display:flex;align-items:center;justify-content:center;background:rgba(13,11,30,.4);cursor:pointer;transition:background .3s}
.sv-player-wrap .sv-play-overlay:hover{background:rgba(13,11,30,.6)}
.sv-player-wrap .sv-play-btn{width:68px;height:68px;background:rgba(108,92,231,.85);border-radius:50%;display:flex;align-items:center;justify-content:center;backdrop-filter:blur(6px)}
.sv-player-wrap .sv-play-btn::after{content:'';display:block;width:0;height:0;border-style:solid;border-width:14px 0 14px 24px;border-color:transparent transparent transparent #fff;margin-left:5px}

/* === 响应式 === */
@media(max-width:1024px){
  .sv-waterfall{column-count:2}
  .sv-experts{grid-template-columns:repeat(2,1fr)}
  .sv-footer-grid{grid-template-columns:1fr 1fr}
  .sv-howto{grid-template-columns:repeat(2,1fr)}
  .sv-contact-grid{grid-template-columns:1fr}
}
@media(max-width:768px){
  .sv-header-inner{flex-wrap:wrap;height:auto;padding:10px 0}
  .sv-search{flex:0 0 100%;order:3;margin-top:10px}
  .sv-nav{display:none;flex-direction:column;width:100%;order:4;padding:10px 0;gap:8px}
  .sv-nav.active{display:flex}
  .sv-menu-btn{display:block}
  .sv-banner{height:380px}
  .sv-banner-content h1{font-size:1.8rem}
  .sv-waterfall{column-count:1}
  .sv-alternate{flex-direction:column!important}
  .sv-alternate-img{flex:none;width:100%}
  .sv-grid6{grid-template-columns:repeat(2,1fr)}
  .sv-experts{grid-template-columns:1fr}
  .sv-review-card{flex:0 0 100%}
  .sv-howto{grid-template-columns:1fr}
  .sv-footer-grid{grid-template-columns:1fr}
  .sv-section{padding:40px 0}
  .sv-section-title h2{font-size:1.5rem}
}
@media(max-width:480px){
  .sv-grid6{grid-template-columns:1fr}
  .sv-contact-qr{flex-direction:column;align-items:center}
}