/* ── 课件学习（学生看课件 · 只看不板书） ── */
  .cw-panel{margin-top:20px;padding:22px}
  .cw-head{display:flex;align-items:flex-start;justify-content:space-between;gap:14px;flex-wrap:wrap}
  .cw-head h2{margin:0;font-size:18px;color:#10213d}
  .cw-head .cw-sub{margin:6px 0 0;color:#52627a;font-size:13px;line-height:1.6;max-width:640px}
  .cw-tabs{display:flex;gap:8px;margin-top:14px;flex-wrap:wrap}
  .cw-tab{min-height:36px;padding:7px 14px;border:1px solid #dfe7f1;border-radius:999px;background:#fff;color:#334155;font-size:13px;font-weight:700;cursor:pointer}
  .cw-tab.on{background:#22304a;color:#fff;border-color:#22304a}
  .cw-hint{margin:12px 2px 2px;color:#64748b;font-size:12.5px;line-height:1.6}
  .cw-subjects{display:grid;grid-template-columns:repeat(auto-fill,minmax(200px,1fr));gap:10px;margin-top:14px}
  .cw-subj{padding:14px;border:1px solid #dfe7f1;border-radius:12px;background:#f7f9fc;color:#10213d;text-align:left;font-weight:800;font-size:14px;cursor:pointer}
  .cw-subj:hover{border-color:#22304a}
  .cw-subj.on{border-color:#1768e5;background:#eaf2ff}
  .cw-subj .cw-cn{display:block;color:#64748b;font-size:11.5px;font-weight:600;margin-top:4px}
  .cw-chapters{display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:10px;margin-top:14px}
  .cw-chap{display:flex;align-items:center;gap:10px;padding:13px 14px;border:1px solid #dfe7f1;border-radius:12px;background:#fff;cursor:pointer;text-align:left;width:100%}
  .cw-chap:hover{border-color:#1768e5;transform:translateY(-1px)}
  .cw-chap .cw-slug{font-family:ui-monospace,Consolas,monospace;color:#1768e5;font-weight:800;font-size:13px;min-width:46px}
  .cw-chap .cw-ctitle{flex:1;font-size:13px;line-height:1.4;color:#17233c}
  .cw-chap .cw-cpages{font-size:11.5px;color:#64748b;white-space:nowrap}
  .cw-empty{margin-top:14px;color:#64748b;font-size:13.5px;line-height:1.6}

  /* 只看阅读器（全屏浮层） */
  #cwViewer{position:fixed;inset:0;background:#0b0d12;display:none;flex-direction:column;z-index:60}
  #cwViewer.on{display:flex}
  /* 房间嫁接：房间跟随态——盖过线上课舞台(z-index:70)，让老师推的课件铺满全屏跟随。
     Bug② robust：room-live 强制 display:flex + 满屏定位，即便 .on 切换有竞态也保证铺满可见。 */
  #cwViewer.room-live{z-index:75;display:flex;position:fixed;inset:0}
  #cwViewer.room-live .cwv-top{box-shadow:inset 0 3px 0 #4ec9a5}
  /* Bug② robust：房间态把「⛶ 全屏」按钮做成醒目实心，学生一眼看到、点一下=用户手势→可靠进OS全屏 */
  #cwViewer.room-live .cwv-fs{background:#4ec9a5;color:#08121f;font-weight:800}
  .cwv-top{display:flex;align-items:center;gap:10px;padding:9px 14px;background:#12151c;border-bottom:1px solid #262b36;flex-wrap:wrap;color:#e6e9ef}
  .cwv-top .cwv-title{font-weight:700;font-size:14px}
  .cwv-top .cwv-title .k{color:#5b9dff;font-family:ui-monospace,Consolas,monospace}
  .cwv-top .cwv-spacer{flex:1}
  .cwv-top button{border:0;border-radius:8px;padding:8px 12px;font-weight:700;cursor:pointer;font-family:inherit;font-size:13px}
  .cwv-top .cwv-fs{background:#2b3342;color:#e6e9ef}
  .cwv-top .cwv-close{background:transparent;border:1px solid #262b36;color:#e6e9ef;font-weight:600}
  .cwv-stagearea{flex:1;position:relative;overflow:hidden;display:flex;align-items:center;justify-content:center;background:#0b0d12}
  #cwvImg{max-width:100%;max-height:calc(100vh - 150px);display:block;background:#fff;border-radius:2px}
  #cwvImg[hidden]{display:none}
  .cwv-fallback{color:#8b93a3;font-size:14px;padding:40px;text-align:center}
  .cwv-bottom{display:flex;align-items:center;gap:10px;padding:9px 14px;background:#12151c;border-top:1px solid #262b36;flex-wrap:wrap;color:#e6e9ef}
  .cwv-bottom button{border:0;border-radius:8px;padding:8px 12px;background:#2b3342;color:#e6e9ef;font-weight:700;cursor:pointer;font-family:inherit;font-size:13px}
  .cwv-bottom button:disabled{opacity:.4;cursor:not-allowed}
  .cwv-pageinfo{font-size:13px;color:#8b93a3;font-family:ui-monospace,Consolas,monospace}
  .cwv-pageinfo b{color:#e6e9ef}
  .cwv-jump{width:56px;text-align:center;padding:7px;border:1px solid #262b36;border-radius:7px;background:#0f1218;color:#e6e9ef;font-family:inherit}
  .cwv-thumbs{display:flex;gap:5px;overflow-x:auto;flex:1;padding:2px 0}
  .cwv-thumb{flex:0 0 auto;width:54px;height:40px;border:2px solid #262b36;border-radius:4px;object-fit:cover;cursor:pointer;background:#fff;opacity:.75}
  .cwv-thumb.on{border-color:#5b9dff;opacity:1}
  .cwv-hint{font-size:11.5px;color:#8b93a3}
  @media(max-width:640px){#cwvImg{max-height:calc(100vh - 200px)}.cwv-hint{display:none}}