/* ============================================================
   离线数学工具箱 · 课件中心  共用样式
   ============================================================ */
:root{
  --bg:#f4f6fa; --panel:#fff; --line:#e3e8f0; --ink:#1f2737; --muted:#6b7684;
  --brand:#2d70b3; --brand-soft:#e8f1fb; --ggb:#c74440; --des:#2d70b3;
  --chip:#eef2f7; --radius:10px;
}
*{box-sizing:border-box}
html,body{margin:0;padding:0}
body{
  font-family:"Microsoft YaHei","PingFang SC","Hiragino Sans GB",system-ui,sans-serif;
  background:var(--bg); color:var(--ink); -webkit-text-size-adjust:100%;
}
a{color:inherit;text-decoration:none}
button{font-family:inherit}

/* ---------------- 目录页 ---------------- */
.top{
  background:linear-gradient(135deg,#2d70b3,#1b4d80); color:#fff;
  padding:20px 24px 18px; position:sticky; top:0; z-index:20;
  box-shadow:0 2px 10px rgba(20,40,70,.14);
}
.top h1{margin:0;font-size:21px;letter-spacing:.4px}
.top .sub{margin:6px 0 0;font-size:12.5px;opacity:.86}
.top .stat{margin-top:8px;font-size:12px;opacity:.8}
.toolbar{max-width:1180px;margin:14px auto 0;padding:0 24px;display:flex;gap:10px;flex-wrap:wrap;align-items:center}
.toolbar input[type=search]{
  flex:1;min-width:200px;padding:9px 12px;font-size:14px;font-family:inherit;
  border:1px solid var(--line);border-radius:var(--radius);outline:none;background:#fff;
}
.toolbar input[type=search]:focus{border-color:var(--brand);box-shadow:0 0 0 3px var(--brand-soft)}
.chips{display:flex;gap:6px;flex-wrap:wrap}
.chip{
  padding:7px 13px;font-size:13px;cursor:pointer;border-radius:999px;
  background:#fff;border:1px solid var(--line);color:var(--muted);transition:.12s;
}
.chip:hover{border-color:#c9dcf2;color:var(--ink)}
.chip.on{background:var(--brand);border-color:var(--brand);color:#fff;font-weight:600}

main{max-width:1180px;margin:0 auto;padding:18px 24px 60px}
.book{margin:6px 0 4px;font-size:13px;font-weight:700;color:var(--brand);
  padding:8px 0 6px;border-bottom:2px solid var(--brand-soft);letter-spacing:.5px}
.chapter{margin:16px 0 6px;font-size:13.5px;font-weight:600;color:#404a5c}
.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(292px,1fr));gap:10px;margin:0 0 10px}
.card{
  display:flex;flex-direction:column;gap:6px;padding:12px 14px;background:var(--panel);
  border:1px solid var(--line);border-radius:var(--radius);cursor:pointer;
  transition:transform .08s,box-shadow .12s,border-color .12s;
}
.card:hover{transform:translateY(-2px);box-shadow:0 6px 18px rgba(30,60,100,.10);border-color:#c9dcf2}
.card:active{transform:translateY(0)}
.card .row{display:flex;align-items:center;gap:8px}
.card .sec{font-size:11.5px;color:var(--muted);font-variant-numeric:tabular-nums}
.card .ttl{font-size:14.5px;font-weight:600;line-height:1.35;flex:1}
.card .txt{font-size:12.5px;color:var(--muted);line-height:1.5}
.badge{
  font-size:11px;padding:2px 8px;border-radius:999px;font-weight:600;white-space:nowrap;
  border:1px solid transparent;
}
.badge.ggb{background:#fdeceb;color:#a93a37;border-color:#f6d3d1}
.badge.des{background:#e8f1fb;color:#1b4d80;border-color:#cfe1f5}
.badge.g3d{background:#efe9f8;color:#4a3282;border-color:#ddd2f0}
.empty{color:var(--muted);text-align:center;padding:60px 0;font-size:14px}
footer.foot{max-width:1180px;margin:0 auto;padding:0 24px 40px;color:var(--muted);font-size:12px;line-height:1.8}

/* ---------------- 播放页 ---------------- */
.app{display:flex;flex-direction:column;height:100vh}
.vhead{
  display:flex;align-items:center;gap:12px;padding:9px 14px;background:#fff;
  border-bottom:1px solid var(--line);flex-wrap:wrap;
}
.vhead .back{
  font-size:13px;color:var(--brand);padding:6px 10px;border-radius:8px;
  border:1px solid var(--line);white-space:nowrap;background:#fff;
}
.vhead .back:hover{background:var(--brand-soft)}
.vhead .meta{flex:1;min-width:180px}
.vhead .path{font-size:11.5px;color:var(--muted)}
.vhead h1{margin:1px 0 0;font-size:15.5px;line-height:1.3}
.vhead .acts{display:flex;gap:6px;align-items:center;flex-wrap:wrap}
.vhead .acts button{
  padding:6px 11px;font-size:12.5px;border-radius:8px;cursor:pointer;
  border:1px solid var(--line);background:#fff;color:var(--muted);
}
.vhead .acts button:hover{background:#f2f5f9;color:var(--ink)}
.switch{display:flex;border:1px solid var(--line);border-radius:8px;overflow:hidden}
.switch button{border:0;border-radius:0;border-right:1px solid var(--line)}
.switch button:last-child{border-right:0}
.switch button.on{background:var(--brand);color:#fff;font-weight:600}
.vdesc{padding:7px 14px;font-size:12.5px;color:var(--muted);background:#fbfcfe;
  border-bottom:1px solid var(--line);line-height:1.6}
#stage{flex:1;min-height:0;position:relative;background:#fff}
#stage .fill{position:absolute;inset:0}
#boot{position:absolute;inset:0;display:flex;align-items:center;justify-content:center;
  color:var(--muted);font-size:14px;background:#fff;z-index:5;text-align:center;padding:20px;line-height:1.8}
.warn{position:absolute;left:10px;bottom:10px;z-index:9;background:#fff5f5;border:1px solid #f6d3d1;
  color:#a93a37;font-size:11.5px;padding:6px 10px;border-radius:8px;max-width:70%;display:none}
kbd{background:#eef2f7;border:1px solid var(--line);border-radius:4px;padding:1px 5px;font-size:11px}

@media (max-width:700px){
  .top{padding:14px 14px}
  .toolbar,main,footer.foot{padding-left:12px;padding-right:12px}
  .vhead{padding:8px}
  .vhead h1{font-size:14px}
}