:root{--bg:#fff;--fg:#0d0d0d;--muted:#6b6b6b;--line:#e7e7e9;--side:#f7f7f8;--gold:#b8892b;--ok:#18a058;font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Inter,Roboto,Arial,sans-serif}
*{box-sizing:border-box;margin:0;padding:0}
body{background:var(--bg);color:var(--fg);font-size:15px;line-height:1.6;padding-bottom:84px}
a{color:inherit}
.topbar{position:sticky;top:0;z-index:30;display:flex;align-items:center;gap:14px;padding:10px 18px;background:#fff;border-bottom:1px solid var(--line)}
.brand img{height:30px;display:block}
.menu-toggle{display:none;background:none;border:0;font-size:22px;cursor:pointer}
.topnav{margin-left:auto;display:flex;gap:18px;align-items:center;font-size:14px}
.topnav a{text-decoration:none;color:var(--muted)}
.topnav a:hover{color:var(--fg)}
.topnav .topcta{background:var(--fg);color:#fff;padding:8px 14px;border-radius:10px;font-weight:600}
.topnav .topcta:hover{color:#fff;opacity:.85}
.app{display:flex;align-items:flex-start}
.sidebar{width:300px;min-width:300px;background:var(--side);border-right:1px solid var(--line);position:sticky;top:51px;height:calc(100vh - 51px);display:flex;flex-direction:column}
.menu{flex:1;overflow-y:auto;padding:8px 10px}
.pillar{font-size:11px;font-weight:700;text-transform:uppercase;letter-spacing:.8px;color:var(--muted);padding:16px 10px 6px}
.item{display:flex;gap:9px;padding:8px 10px;border-radius:9px;text-decoration:none;font-size:13.5px;line-height:1.45}
.item:hover{background:#ececee}
.item.active{background:#e6e6e9;font-weight:600}
.tick{flex:0 0 16px;height:16px;border:1.5px solid #c9c9cd;border-radius:50%;margin-top:2px;position:relative}
.item.done .tick{background:var(--ok);border-color:var(--ok)}
.item.done .tick::after{content:"";position:absolute;left:4.5px;top:1.5px;width:4px;height:8px;border:solid #fff;border-width:0 2px 2px 0;transform:rotate(45deg)}
.side-foot{padding:12px 18px 16px;border-top:1px solid var(--line);font-size:12.5px;color:var(--muted)}
.bar{height:6px;background:#e3e3e6;border-radius:4px;margin-top:6px;overflow:hidden}
#progressFill{height:100%;background:var(--ok);width:0}
.main{flex:1;min-width:0}
.content{max-width:860px;margin:0 auto;padding:28px 22px 10px}
.kicker{font-size:12px;text-transform:uppercase;letter-spacing:.8px;color:var(--gold);font-weight:700}
h1{font-size:26px;line-height:1.25;margin:6px 0 18px}
.video{position:relative;width:100%;aspect-ratio:16/9;background:#000;border-radius:12px;overflow:hidden}
.video iframe{position:absolute;inset:0;width:100%;height:100%;border:0}
.about{margin:18px 0;color:#333}
.mark{margin-top:6px;padding:10px 18px;border-radius:10px;border:1px solid var(--line);background:#fff;cursor:pointer;font-size:14px;font-weight:600}
.mark.done{background:var(--ok);color:#fff;border-color:var(--ok)}
.btn{display:inline-block;background:var(--fg);color:#fff;text-decoration:none;padding:10px 18px;border-radius:10px;font-weight:600;font-size:14px}
.btn.big{padding:14px 24px;font-size:16px;margin:8px 0 28px}
.tools{margin:26px 0;padding:20px;border:1px solid var(--line);border-radius:14px;background:var(--side)}
.tools h2{font-size:19px;margin-bottom:6px}
.tool-grid{display:grid;grid-template-columns:1fr 1fr;gap:14px;margin:14px 0}
.tool{background:#fff;border:1px solid var(--line);border-radius:12px;padding:16px}
.tool h3{margin-bottom:4px}.tool p{color:var(--muted);margin-bottom:12px;font-size:14px}
.disc{font-size:12.5px;color:var(--muted)}
.lesson-nav{max-width:860px;margin:10px auto 0;padding:0 22px;display:flex;justify-content:space-between;gap:12px;font-size:14px}
.lesson-nav a{text-decoration:none;color:var(--muted)}.lesson-nav a:hover{color:var(--fg)}
.foot{max-width:860px;margin:36px auto 0;padding:18px 22px 30px;border-top:1px solid var(--line);font-size:12px;color:var(--muted)}
.foot p{margin-bottom:8px}
.sticky{position:fixed;left:0;right:0;bottom:0;z-index:40;display:flex;align-items:center;justify-content:center;gap:16px;flex-wrap:wrap;padding:12px 16px;background:#0d0d0d;color:#fff;box-shadow:0 -4px 18px rgba(0,0,0,.18)}
.sticky-q{font-weight:600}
.sticky-btn{background:var(--gold);color:#fff;text-decoration:none;padding:10px 18px;border-radius:10px;font-weight:700;font-size:14px}
@media(max-width:860px){
  .menu-toggle{display:block}
  .topnav a:not(.topcta){display:none}
  .topnav .topcta{display:none}
  .sidebar{position:fixed;top:51px;left:0;z-index:35;transform:translateX(-100%);transition:transform .2s;box-shadow:4px 0 18px rgba(0,0,0,.15)}
  .sidebar.open{transform:none}
  .tool-grid{grid-template-columns:1fr}
  h1{font-size:21px}
  .sticky{gap:8px;padding:10px 12px}.sticky-q{font-size:13px;width:100%;text-align:center}.sticky-btn{width:100%;text-align:center}
  body{padding-bottom:110px}
}