:root{
  --bg:#0f172a;
  --panel:#111827;
  --panel-2:#0b1220;
  --text:#e5e7eb;
  --muted:#9ca3af;
  --accent:#7c3aed;
  --accent-2:#a855f7;
  --border:#1f2937;
}
*{box-sizing:border-box}
html,body{height:100%}
body{
  margin:0;
  background:var(--bg);
  color:var(--text);
  font:14px/1.55 'Inter', system-ui, -apple-system, Segoe UI, Roboto, Ubuntu, Cantarell, Noto Sans, Helvetica, Arial, Apple Color Emoji, Segoe UI Emoji;
}
.app{display:flex;flex-direction:column;height:100vh}
.topbar{display:flex;align-items:center;justify-content:space-between;padding:10px 16px;border-bottom:1px solid var(--border);background:var(--panel);position:sticky;top:0;z-index:10;backdrop-filter:saturate(1.2) blur(6px)}
.brand{font-weight:700;letter-spacing:.3px}
.actions{display:flex;gap:10px;align-items:center}
.search{background:var(--panel-2);border:1px solid var(--border);color:var(--text);padding:10px 12px;border-radius:10px;min-width:260px}
.btn{background:#111827;border:1px solid var(--border);color:var(--text);padding:8px 12px;border-radius:10px;cursor:pointer;transition:transform .06s ease, background .2s ease, border-color .2s ease}
.btn:hover{background:#0f1626;border-color:#324155}
.btn:active{transform:translateY(1px)}
.btn.primary{background:linear-gradient(135deg,var(--accent),var(--accent-2));border:none}
.btn:disabled{opacity:.5;cursor:not-allowed}

.main{display:flex;min-height:0;flex:1}
.sidebar{width:320px;border-right:1px solid var(--border);background:var(--panel-2);overflow:auto}
.sidebar.hidden{display:none}
.course-list{padding:8px}
.course{border:1px solid var(--border);border-radius:12px;margin:10px 0;background:linear-gradient(180deg,var(--panel),#0e1626);box-shadow:0 4px 20px rgba(0,0,0,.2)}
.course-header{display:flex;align-items:center;justify-content:space-between;padding:10px 12px;cursor:pointer}
.course-title{font-weight:600}
.module{border-top:1px solid var(--border)}
.module-header{padding:10px 12px;color:#cbd5e1;cursor:pointer;display:flex;align-items:center;gap:8px}
.caret{display:inline-block;transition:transform .15s ease;}
.module.collapsed .caret{transform:rotate(-90deg)}
.module.collapsed .lecture{display:none}
.lecture{display:flex;align-items:center;gap:8px;padding:10px 12px;border-top:1px dashed var(--border);cursor:pointer;border-left:2px solid transparent}
.lecture:hover{background:#0f172a}
.lecture .dot{width:8px;height:8px;border-radius:50%;background:var(--muted);box-shadow:0 0 0 1px rgba(255,255,255,.05) inset}
.lecture.active{background:#0b1220}
.lecture.completed .dot{background:#22c55e}

.content{display:flex;flex-direction:column;flex:1;min-width:0}
.player{position:relative;display:grid;grid-template-rows:auto;grid-template-columns:1fr;min-height:320px;border-bottom:1px solid var(--border);background:black}
video, iframe{width:100%;height:60vh;max-height:70vh;border:0;display:none;background:black}
video.active, iframe.active{display:block}
.controls-bar{position:absolute;left:0;right:0;bottom:0;display:flex;flex-direction:column;gap:8px;padding:10px;background:linear-gradient(180deg, rgba(0,0,0,0) 0%, rgba(0,0,0,.5) 30%, rgba(0,0,0,.85) 100%);opacity:0;transition:opacity .2s;z-index:3}
.player:hover .controls-bar, .player.active .controls-bar{opacity:1}
.controls-bar .row{display:flex;align-items:center;gap:10px}
.controls-bar .row.bottom{justify-content:space-between}
.controls-bar .left, .controls-bar .right{display:flex;align-items:center;gap:10px}
.controls-bar .icon{padding:0; width:36px; height:36px; display:inline-flex; align-items:center; justify-content:center; border-radius:6px; line-height:0}
.controls-bar .icon svg, .controls-bar .icon i{width:20px; height:20px; display:block; flex:0 0 auto; font-size:20px}
.controls-bar .time{min-width:110px;color:#ddd}
.controls-bar select{background:#111827;border:1px solid var(--border);color:var(--text);border-radius:6px;padding:4px}
.volume{display:flex;align-items:center;gap:6px}
.volume input[type="range"]{width:0;transition:width .2s;overflow:hidden}
.right .volume:hover input[type="range"]{width:100px}
.settings{position:relative}
.menu{position:absolute;right:0;bottom:36px;background:#0b1220;border:1px solid var(--border);border-radius:8px;min-width:160px;display:none;box-shadow:0 10px 30px rgba(0,0,0,.4)}
.menu.open{display:block}
.menu-title{padding:8px 12px;color:#9ca3af;border-bottom:1px solid var(--border)}
.menu-item{display:block;background:transparent;border:0;color:#e5e7eb;width:100%;text-align:left;padding:10px 12px;cursor:pointer}
.menu-item:hover{background:#0f172a}
#subtitleList{max-height:220px;overflow:auto}
.menu-section{padding:6px 0}
.menu-subtitle{padding:8px 12px;color:#9ca3af}
.menu-row{display:flex;gap:6px;flex-wrap:wrap;padding:6px 10px}
.menu-row .menu-item{width:auto}

/* Subtitle cue appearance */
video::cue{
  color:#fff;
  background:rgba(0,0,0,var(--cue-bg,0.6));
  font-size:var(--cue-size,1em);
  text-shadow: 0 2px 4px rgba(0,0,0,.8);
}
.seekbar{position:relative;height:6px;border-radius:999px;background:rgba(255,255,255,0.2);overflow:hidden;cursor:pointer;width:100%;touch-action:none}
.seekbar-buffered{position:absolute;left:0;top:0;bottom:0;background:rgba(255,255,255,0.35);width:0}
.seekbar-played{position:absolute;left:0;top:0;bottom:0;background:#f00;width:0}
.seekbar-thumb{position:absolute;top:50%;transform:translate(-50%,-50%);width:12px;height:12px;border-radius:50%;background:#fff;box-shadow:0 0 0 2px rgba(255,255,255,.6);left:0}
.player.theater{min-height:75vh}
.player.theater video, .player.theater iframe{height:75vh;max-height:none}
/* Nudge controls slightly lower in theater mode */
.player.theater .controls-bar{bottom:-6px;padding-bottom:16px}

.details{padding:12px}
.controls{display:flex;gap:8px;margin:8px 0}
.notes textarea{width:100%;min-height:140px;background:var(--panel-2);border:1px solid var(--border);color:var(--text);padding:10px;border-radius:8px}
.notes textarea:focus{outline:2px solid #334155}

.empty{padding:20px;color:var(--muted)}

/* Scrollbars */
*::-webkit-scrollbar{height:10px;width:10px}
*::-webkit-scrollbar-track{background:transparent}
*::-webkit-scrollbar-thumb{background:#1f2937;border-radius:10px;border:2px solid transparent;background-clip:content-box}
*::-webkit-scrollbar-thumb:hover{background:#273244;background-clip:content-box}

@media (max-width: 900px){
  .sidebar{width:280px}
  video, iframe{height:45vh}
}

/* Ensure theater mode wins over mobile height rules */
.player.theater video, .player.theater iframe{height:75vh;max-height:none}

/* Fullscreen styles */
#playerContainer:fullscreen{width:100vw;height:100vh;background:black}
#playerContainer:fullscreen video, #playerContainer:fullscreen iframe{height:100vh;max-height:none}
#playerContainer:fullscreen .controls-bar{bottom:0;padding-bottom:10px}
#playerContainer:fullscreen ~ .details{display:none}

/* Fullscreen layout including sidebar */
#mainContainer:fullscreen{width:100vw;height:100vh;display:grid;grid-template-columns:320px 1fr;grid-template-rows:1fr;background:var(--bg)}
#mainContainer:fullscreen .sidebar{display:block}
#mainContainer:fullscreen .sidebar.hidden{display:none}
#mainContainer:fullscreen .sidebar.hidden + .content{grid-column:1 / -1}
#mainContainer:fullscreen .content{display:flex;flex-direction:column}
#mainContainer:fullscreen .player{min-height:100vh;border-bottom:0}
#mainContainer:fullscreen .player video, #mainContainer:fullscreen .player iframe{height:100vh;max-height:none}
#mainContainer:fullscreen .player .controls-bar{bottom:0;padding-bottom:10px}
#mainContainer:fullscreen .details{display:none}

#mainContainer:-webkit-full-screen{width:100vw;height:100vh;display:grid;grid-template-columns:320px 1fr;grid-template-rows:1fr;background:var(--bg)}
#mainContainer:-webkit-full-screen .sidebar{display:block}
#mainContainer:-webkit-full-screen .sidebar.hidden{display:none}
#mainContainer:-webkit-full-screen .sidebar.hidden + .content{grid-column:1 / -1}
#mainContainer:-webkit-full-screen .content{display:flex;flex-direction:column}
#mainContainer:-webkit-full-screen .player{min-height:100vh;border-bottom:0}
#mainContainer:-webkit-full-screen .player video, #mainContainer:-webkit-full-screen .player iframe{height:100vh;max-height:none}
#mainContainer:-webkit-full-screen .player .controls-bar{bottom:0;padding-bottom:10px}
#mainContainer:-webkit-full-screen .details{display:none}
#playerContainer:-webkit-full-screen{width:100vw;height:100vh;background:black}
#playerContainer:-webkit-full-screen video, #playerContainer:-webkit-full-screen iframe{height:100vh;max-height:none}
#playerContainer:-webkit-full-screen .controls-bar{bottom:0;padding-bottom:10px}