:root{
  --gold:#ddc57c; --gold-d:#d2b354; --slate:#30373d; --ink:#2b2f33; --muted:#748493;
  --bg:#f6f8f9; --card:#ffffff; --line:#ececec; --line-2:#e5e9e9;
}
*{box-sizing:border-box} html,body{margin:0}
body{font-family:'Roboto',system-ui,-apple-system,Segoe UI,Arial,sans-serif;color:var(--ink);background:var(--bg);line-height:1.5}
h1,h2,h3,.brand-name,.course-pill,.module-title{font-family:'Oswald',sans-serif;letter-spacing:.02em}
a{color:inherit;text-decoration:none}

.topbar{position:sticky;top:0;z-index:40;display:flex;align-items:center;gap:16px;height:60px;padding:0 18px;background:var(--slate);color:#fff;box-shadow:0 1px 0 rgba(0,0,0,.2)}
.topbar .brand{display:flex;align-items:center;gap:12px}
.topbar .brand img{height:34px;width:auto;display:block}
.brand-name{font-size:17px;font-weight:600;color:#fff;letter-spacing:.06em}
.course-pill{margin-left:auto;font-size:14px;font-weight:500;color:var(--slate);background:var(--gold);padding:6px 14px;border-radius:999px;text-transform:uppercase}
.burger{display:none;background:none;border:0;color:#fff;font-size:22px;cursor:pointer;padding:4px 8px}

.layout{display:flex;align-items:flex-start;max-width:1500px;margin:0 auto}
.sidebar{width:360px;flex:0 0 360px;background:var(--card);border-right:1px solid var(--line);min-height:calc(100vh - 60px);position:sticky;top:60px;max-height:calc(100vh - 60px);overflow-y:auto}
.course-head{padding:22px 22px 16px;border-bottom:1px solid var(--line)}
.course-title{margin:0 0 6px;font-size:22px;color:var(--slate);text-transform:uppercase}
.course-meta{font-size:12.5px;color:var(--muted);margin-bottom:14px}
.progress-wrap{display:flex;align-items:center;gap:10px}
.progress-bar{flex:1;height:8px;background:var(--line);border-radius:999px;overflow:hidden}
.progress-bar span{display:block;height:100%;width:0;background:linear-gradient(90deg,var(--gold),var(--gold-d));transition:width .4s}
.progress-label{font-size:12px;font-weight:700;color:var(--gold-d);min-width:34px;text-align:right}

.module{border-bottom:1px solid var(--line)}
.module-head{display:flex;align-items:center;gap:10px;width:100%;padding:15px 20px;background:none;border:0;cursor:pointer;text-align:left}
.module-title{flex:1;font-size:14.5px;font-weight:600;color:var(--slate);text-transform:uppercase}
.module-count{font-size:11px;color:var(--muted);font-family:'Roboto'}
.module-chevron{color:var(--muted);transition:transform .25s;font-size:12px}
.module.collapsed .module-chevron{transform:rotate(-90deg)}
.module.collapsed .lessons{display:none}
.lessons{padding:2px 0 8px}
.lesson{display:flex;align-items:center;gap:12px;padding:10px 20px 10px 22px;cursor:pointer;border-left:3px solid transparent}
.lesson:hover{background:#faf9f4}
.lesson.active{background:#fbf6e8;border-left-color:var(--gold)}
.lesson .tick{flex:0 0 20px;height:20px;width:20px;border-radius:50%;border:2px solid var(--line-2);display:grid;place-items:center;font-size:11px;color:#fff}
.lesson.done .tick{background:var(--gold-d);border-color:var(--gold-d)}
.lesson .ico{flex:0 0 auto;color:var(--muted);font-size:12px}
.lesson .lx{flex:1;min-width:0}
.lesson .lt{font-size:13.5px;color:var(--ink);white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.lesson.active .lt{font-weight:700;color:var(--slate)}
.lesson .ld{font-size:11px;color:var(--muted)}

.main{flex:1;min-width:0;padding:26px 34px 60px}
.player-shell{background:#000;border-radius:12px;overflow:hidden;box-shadow:0 10px 30px rgba(48,55,61,.18)}
.player{position:relative;width:100%;aspect-ratio:16/9;background:#000}
.player video{width:100%;height:100%;display:block;background:#000}
.lesson-head{padding:22px 2px 0}
.lesson-module{font-size:12px;font-weight:700;letter-spacing:.08em;text-transform:uppercase;color:var(--gold-d)}
.lesson-title{margin:6px 0 18px;font-size:26px;color:var(--slate)}
.lesson-actions{display:flex;align-items:center;gap:16px;flex-wrap:wrap}
.btn{font-family:'Oswald';text-transform:uppercase;font-size:13px;letter-spacing:.04em;border:1px solid var(--line-2);background:#fff;color:var(--slate);padding:10px 18px;border-radius:8px;cursor:pointer;transition:.15s}
.btn:hover{border-color:var(--gold-d);color:var(--gold-d)}
.btn:disabled{opacity:.4;cursor:not-allowed}
.btn-next{background:var(--slate);color:#fff;border-color:var(--slate)}
.btn-next:hover{background:var(--gold-d);border-color:var(--gold-d);color:#fff}
.done-toggle{display:flex;align-items:center;gap:8px;font-size:13px;color:var(--muted);cursor:pointer;margin-left:auto}
.done-toggle input{width:17px;height:17px;accent-color:var(--gold-d)}

.scrim{display:none;position:fixed;inset:60px 0 0;background:rgba(0,0,0,.4);z-index:30}
@media(max-width:900px){
  .burger{display:block}
  .sidebar{position:fixed;top:60px;left:0;z-index:35;transform:translateX(-100%);transition:transform .25s;box-shadow:2px 0 20px rgba(0,0,0,.2)}
  .sidebar.open{transform:none}
  .scrim.show{display:block}
  .brand-name{display:none}
  .main{padding:16px}
  .lesson-title{font-size:21px}
}