:root{
  --bg:#ffffff; --fg:#0d0d0d; --muted:#6b6b6b; --line:#e7e7e9;
  --side:#f7f7f8; --accent:#0d0d0d; --hover:#ececee; --ok:#18a058; --radius:12px;
  font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Inter,Roboto,Helvetica,Arial,sans-serif;
}
*{box-sizing:border-box;margin:0;padding:0}
html,body{height:100%}
body{background:var(--bg);color:var(--fg);font-size:15px;line-height:1.6;-webkit-font-smoothing:antialiased}
.hidden{display:none !important}

/* GATE */
.gate{position:fixed;inset:0;background:var(--bg);display:flex;align-items:center;justify-content:center;z-index:50}
.gate-card{text-align:center;width:min(360px,90vw)}
.logo{font-size:26px;font-weight:700;letter-spacing:-.5px}
.logo span{color:var(--muted);font-weight:400;margin-left:6px}
.logo.small{font-size:17px}
.gate-sub{color:var(--muted);margin:14px 0 26px}
#pin{width:100%;padding:13px 16px;font-size:18px;text-align:center;letter-spacing:8px;border:1px solid var(--line);border-radius:var(--radius);outline:none;background:#fafafa}
#pin:focus{border-color:#bbb;background:#fff}
#pinBtn{margin-top:14px;width:100%;padding:12px;border:0;border-radius:var(--radius);background:var(--accent);color:#fff;font-size:15px;font-weight:600;cursor:pointer}
#pinBtn:hover{opacity:.85}
.pin-err{color:#d03050;font-size:13px;margin-top:10px;visibility:hidden}
.pin-err.show{visibility:visible}

/* LAYOUT */
.app{display:flex;height:100vh;overflow:hidden}
.sidebar{width:288px;min-width:288px;background:var(--side);border-right:1px solid var(--line);display:flex;flex-direction:column;transition:margin .2s}
.sidebar.closed{margin-left:-288px}
.brand{display:flex;align-items:center;justify-content:space-between;padding:18px 18px 12px}
.collapse,.menu-toggle{background:none;border:0;font-size:18px;cursor:pointer;color:var(--muted);padding:4px 8px;border-radius:8px}
.collapse:hover,.menu-toggle:hover{background:var(--hover)}
.menu{flex:1;overflow-y:auto;padding:6px 10px 14px}
.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;align-items:flex-start;padding:8px 10px;border-radius:9px;cursor:pointer;color:var(--fg);text-decoration:none;font-size:13.5px;line-height:1.45}
.item:hover{background:var(--hover)}
.item.active{background:#e6e6e9;font-weight:600}
.item .tick{flex:0 0 16px;height:16px;border:1.5px solid #c9c9cd;border-radius:50%;margin-top:2px;position:relative;min-width:16px}
.item.done .tick{background:var(--ok);border-color:var(--ok)}
.item.done .tick::after{content:"";position:absolute;left:4.6px;top:2.2px;width:4px;height:8px;border:solid #fff;border-width:0 2px 2px 0;transform:rotate(45deg)}
.item .t{flex:1}
.item.no-video .tick{border-style:dashed}
.side-foot{padding:14px 18px;border-top:1px solid var(--line);font-size:12px;color:var(--muted)}
.progress-bar{height:5px;background:#e3e3e6;border-radius:99px;margin-top:7px;overflow:hidden}
#progressFill{height:100%;width:0;background:var(--ok);border-radius:99px;transition:width .3s}

.main{flex:1;display:flex;flex-direction:column;overflow:hidden}
.topbar{display:flex;align-items:center;gap:10px;padding:12px 26px;border-bottom:1px solid var(--line);background:rgba(255,255,255,.9);backdrop-filter:blur(6px)}
.crumb{font-size:13px;color:var(--muted)}
.content{flex:1;overflow-y:auto;padding:34px 40px 60px;max-width:980px;width:100%;margin:0 auto}
.content h1{font-size:26px;letter-spacing:-.6px;margin-bottom:6px}
.kicker{font-size:12px;text-transform:uppercase;letter-spacing:1px;color:var(--muted);margin-bottom:14px}
.video{position:relative;width:100%;aspect-ratio:16/9;border-radius:var(--radius);overflow:hidden;background:#000;margin:18px 0 26px;border:1px solid var(--line)}
.video iframe{position:absolute;inset:0;width:100%;height:100%;border:0}
.video .novid{position:absolute;inset:0;display:flex;flex-direction:column;gap:6px;align-items:center;justify-content:center;color:#bbb;background:repeating-linear-gradient(45deg,#111,#111 14px,#161616 14px,#161616 28px)}
.video .novid b{color:#eee;font-size:15px}
.about{white-space:pre-wrap;font-size:15.5px;color:#242424}
.about a{color:var(--fg)}
.pill{display:inline-block;font-size:11.5px;background:var(--side);border:1px solid var(--line);color:var(--muted);border-radius:99px;padding:2px 10px;margin-left:8px;vertical-align:2px}
.mark{margin-top:26px;display:inline-flex;gap:8px;align-items:center;background:var(--accent);color:#fff;border:0;border-radius:10px;padding:10px 18px;font-size:14px;font-weight:600;cursor:pointer}
.mark.done{background:var(--ok)}
.mark:hover{opacity:.88}
.lesson-nav{display:flex;justify-content:space-between;gap:12px;padding:14px 40px;border-top:1px solid var(--line)}
.lesson-nav a{font-size:13.5px;color:var(--fg);text-decoration:none;padding:9px 14px;border:1px solid var(--line);border-radius:10px;max-width:48%}
.lesson-nav a:hover{background:var(--hover)}
.lesson-nav .spacer{flex:1}

.menu-toggle{display:none}
@media (max-width:860px){
  .sidebar{position:fixed;z-index:40;height:100%;box-shadow:2px 0 24px rgba(0,0,0,.08)}
  .sidebar.closed{transform:translateX(-100%);margin-left:0}
  .menu-toggle{display:block}
  .content{padding:22px 18px 50px}
  .lesson-nav{padding:12px 18px}
}