:root{
      --primary:#0B3D91;
      --primary-dark:#082d6b;
      --ink:#172033;
      --muted:#667085;
      --line:#e5e9f0;
      --soft:#f4f7fb;
      --white:#fff;
      --shadow:0 16px 45px rgba(12,38,78,.10);
      --radius:18px;
    }
    *{box-sizing:border-box}
    html{scroll-behavior:smooth}
    body{margin:0;color:var(--ink);background:#f8fafc;font-family:"Microsoft YaHei","PingFang SC",Arial,sans-serif;line-height:1.7}
    a{color:inherit;text-decoration:none}
    img{max-width:100%;display:block}
    button{font:inherit}
    .container{width:min(1180px,calc(100% - 40px));margin:0 auto}

    .topbar{background:#092d68;color:#dbe8ff;font-size:13px}
    .topbar .container{min-height:36px;display:flex;align-items:center;justify-content:space-between}
    .topbar a{color:#fff;margin-left:20px}
    .header{position:relative;z-index:20;background:#fff;border-bottom:1px solid var(--line)}
    .header-inner{height:78px;display:flex;align-items:center;gap:34px}
    .logo{display:flex;align-items:center;gap:10px;min-width:180px;font-weight:800;font-size:19px;color:var(--primary)}
    .logo img{width:38px;height:38px;object-fit:contain}
    .main-nav{flex:1}
    .nav-list{display:flex;align-items:center;justify-content:center;gap:4px;list-style:none;padding:0;margin:0}
    .nav-item{position:relative}
    .nav-link{display:flex;align-items:center;gap:5px;padding:27px 13px;font-size:15px;color:#25324a;white-space:nowrap}
    .nav-link:hover{color:var(--primary)}
    .has-arrow:after{content:"";width:6px;height:6px;border-right:1px solid currentColor;border-bottom:1px solid currentColor;transform:rotate(45deg) translateY(-2px)}
    .dropdown-panel,.mega-menu{position:absolute;top:100%;left:50%;transform:translateX(-50%);width:270px;padding:14px;background:#fff;border:1px solid var(--line);border-radius:0 0 14px 14px;box-shadow:var(--shadow);opacity:0;visibility:hidden;transition:.2s;z-index:30}
    .mega-menu{width:650px}
    .nav-item:after{content:"";position:absolute;left:0;right:0;height:14px;top:100%}
    .nav-item:hover>.dropdown-panel,.nav-item:focus-within>.dropdown-panel,.nav-item:hover>.mega-menu,.nav-item:focus-within>.mega-menu{opacity:1;visibility:visible}
    .dropdown-panel>a:not(.mega-footer){display:block;padding:10px 12px;border-bottom:1px solid #eef1f5;font-size:14px}
    .dropdown-panel>a:hover,.mega-card:hover{color:var(--primary);background:#f5f8fd}
    .mega-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:10px}
    .mega-card{display:block;min-height:100px;padding:10px;border:1px solid #edf0f5;border-radius:10px;transition:.2s}
    .mega-card img{width:38px;height:38px;object-fit:cover;border-radius:8px;margin-bottom:7px}
    .mega-card strong{display:block;font-size:13px;line-height:1.4}
    .mega-card small{display:block;margin-top:4px;color:var(--muted);font-size:11px;line-height:1.5}
    .mega-footer{display:block;text-align:center;margin-top:12px;padding:10px;background:var(--primary);border-radius:8px;color:#fff;font-size:13px}
    .header-btns{display:flex;align-items:center;gap:14px;white-space:nowrap}
    .account-link{padding:9px 15px;background:var(--primary);color:#fff;border-radius:8px;font-size:13px}
    .hamburger{display:none;width:40px;height:38px;border:1px solid var(--line);background:#fff;border-radius:8px;padding:8px;cursor:pointer}
    .hamburger span{display:block;height:2px;background:var(--primary);margin:4px 0;transition:.2s}
    .hamburger.active span:nth-child(1){transform:translateY(6px) rotate(45deg)}
    .hamburger.active span:nth-child(2){opacity:0}
    .hamburger.active span:nth-child(3){transform:translateY(-6px) rotate(-45deg)}

    .drawer-overlay{display:none;position:fixed;inset:0;background:rgba(6,20,45,.48);z-index:80}
    .drawer-overlay.open{display:block}
    .mobile-drawer{position:fixed;top:0;right:-360px;width:min(360px,88vw);height:100vh;background:#fff;z-index:90;overflow:auto;transition:right .25s;box-shadow:-12px 0 35px rgba(0,0,0,.16)}
    .mobile-drawer.open{right:0}
    .drawer-head{display:flex;align-items:center;gap:15px;padding:20px;border-bottom:1px solid var(--line);font-weight:700;color:var(--primary)}
    .drawer-head>a{margin-left:auto;padding:6px 12px;border-radius:6px;background:var(--primary);color:#fff;font-size:13px}
    .drawer-close{border:0;background:none;font-size:28px;color:#667085;cursor:pointer;line-height:1}
    .drawer-menu{padding:10px 20px 30px}
    .drawer-link,.drawer-toggle{display:block;width:100%;padding:14px 0;border:0;border-bottom:1px solid var(--line);background:none;text-align:left;color:var(--ink);font-size:15px;cursor:pointer}
    .drawer-toggle:after{content:"+";float:right;color:var(--primary);font-size:20px}
    .drawer-toggle.active:after{content:"−"}
    .drawer-submenu{display:none;padding:5px 0 8px 14px}
    .drawer-submenu.open{display:block}
    .drawer-submenu a{display:block;padding:8px 0;color:var(--muted);font-size:14px}

    .video-detail-main{padding:54px 0 80px}
    .video-breadcrumb{color:var(--muted);font-size:14px;margin-bottom:22px}
    .video-breadcrumb a{color:var(--primary)}
    .video-article{max-width:1000px;margin:0 auto}
    .video-heading{margin-bottom:26px}
    .video-heading h1{font-size:clamp(28px,4vw,46px);line-height:1.25;margin:0 0 16px;color:#12213c}
    .video-meta{display:flex;flex-wrap:wrap;gap:18px;color:var(--muted);font-size:14px}
    .video-player{position:relative;overflow:hidden;background:#071329;border-radius:18px;box-shadow:var(--shadow);aspect-ratio:16/9;margin-bottom:28px}
    .video-player img{width:100%;height:100%;object-fit:cover;opacity:.72}
    .video-player:after{content:"";position:absolute;inset:0;background:linear-gradient(0deg,rgba(4,13,30,.72),rgba(4,13,30,.05))}
    .video-player .player-overlay{position:absolute;z-index:2;inset:0;display:flex;align-items:center;justify-content:center}
    .play-button{width:78px;height:78px;border:0;border-radius:50%;background:#fff;color:var(--primary);font-size:31px;padding-left:7px;cursor:pointer;box-shadow:0 8px 25px rgba(0,0,0,.25)}
    .player-caption{position:absolute;z-index:3;left:28px;right:28px;bottom:22px;color:#fff;font-size:14px}
    .player-caption span{display:inline-block;margin-right:8px;padding:4px 9px;border-radius:5px;background:var(--primary)}
    .video-layout{display:grid;grid-template-columns:minmax(0,1fr) 290px;gap:28px;align-items:start}
    .video-content-card,.related-videos{background:#fff;border:1px solid var(--line);border-radius:var(--radius);box-shadow:0 7px 25px rgba(20,40,75,.05)}
    .video-content-card{padding:30px}
    .video-content-card h2,.related-videos h2{font-size:20px;margin:0 0 18px;color:#12213c}
    .video-summary{padding:16px 18px;background:#f4f7fc;border-left:4px solid var(--primary);border-radius:8px;color:#46556d;margin-bottom:24px}
    .video-body{min-width:0;max-width:100%;overflow-x:auto;color:#334155}
    .video-body img,.video-body table{max-width:100%}
    .video-body table{border-collapse:collapse}
    .video-body p{margin:0 0 18px}
    .video-tags{display:flex;flex-wrap:wrap;gap:8px;margin-top:26px;padding-top:20px;border-top:1px solid var(--line)}
    .video-tags a{padding:5px 10px;background:#eef4ff;color:var(--primary);border-radius:20px;font-size:13px}
    .related-videos{padding:22px}
    .related-videos h2{font-size:18px}
    .related-card{display:block;padding:12px 0;border-bottom:1px solid var(--line)}
    .related-card:last-child{border-bottom:0}
    .related-card img{width:100%;aspect-ratio:16/9;object-fit:cover;border-radius:8px;margin-bottom:8px}
    .related-card strong{display:block;font-size:14px;line-height:1.5}
    .related-card small{display:block;color:var(--muted);font-size:12px;margin-top:4px}
    .video-actions{display:flex;justify-content:space-between;gap:15px;margin-top:28px;padding-top:22px;border-top:1px solid var(--line)}
    .video-actions a{display:inline-block;padding:10px 16px;border:1px solid var(--line);border-radius:8px;color:var(--primary);font-size:14px}
    .video-actions a.primary-action{background:var(--primary);border-color:var(--primary);color:#fff}

    .footer{background:#0a1e40;color:#c6d2e6;padding:58px 0 20px}
    .footer-grid{display:grid;grid-template-columns:1.5fr 1fr 1fr 1fr;gap:35px}
    .footer h3{color:#fff;font-size:16px;margin:0 0 17px}
    .footer p{margin:0 0 10px;font-size:13px;line-height:1.9}
    .footer a{display:block;margin:7px 0;color:#c6d2e6;font-size:13px}
    .footer a:hover{color:#fff}
    .footer-bottom{border-top:1px solid rgba(255,255,255,.14);margin-top:36px;padding-top:18px;text-align:center;color:#8fa2bf;font-size:12px}

    @media(max-width:1050px){
      .header-inner{gap:15px}
      .logo{min-width:145px}
      .nav-link{padding-left:8px;padding-right:8px}
      .mega-menu{width:580px}
    }
    @media(max-width:820px){
      .container{width:min(100% - 28px,680px)}
      .topbar .container{min-height:42px}
      .topbar .contact a{margin-left:10px}
      .main-nav{display:none}
      .hamburger{display:block}
      .header-inner{height:68px}
      .logo{min-width:0}
      .video-detail-main{padding:32px 0 55px}
      .video-layout{grid-template-columns:1fr}
      .related-videos{display:grid;grid-template-columns:repeat(2,1fr);gap:15px}
      .related-videos h2{grid-column:1/-1;margin-bottom:0}
      .related-card{border:0;padding:0}
      .footer-grid{grid-template-columns:repeat(2,1fr);gap:25px}
    }
    @media(max-width:520px){
      .topbar .container{display:block;padding:7px 0}
      .topbar .contact{display:block}
      .topbar .contact a{margin:2px 12px 0 0}
      .header-btns{gap:8px}
      .account-link{padding:8px 10px;font-size:12px}
      .logo{font-size:16px}
      .logo img{width:32px;height:32px}
      .video-heading h1{font-size:29px}
      .video-player{border-radius:12px}
      .player-caption{left:15px;right:15px;bottom:12px;font-size:12px}
      .play-button{width:58px;height:58px;font-size:24px}
      .video-content-card{padding:20px}
      .related-videos{display:block}
      .related-card{padding:12px 0;border-bottom:1px solid var(--line)}
      .footer-grid{grid-template-columns:1fr}
      .video-actions{display:block}
      .video-actions a{display:block;text-align:center;margin-top:10px}
    }