:root{color-scheme:dark;--bg:#0c2026;--panel:#15343b;--card:#20464d;--line:#45666b;--text:#f4f8ef;--muted:#bfceca;--accent:#cbe78b;--ink:#16332a;--good:#bcefb2;--bad:#ffd4b5}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--text);font-family:"Microsoft YaHei","PingFang SC",sans-serif;font-size:20px;line-height:1.5}body.contrast{--bg:#000;--panel:#101010;--card:#191919;--line:#b5b5b5;--text:#fff;--muted:#eee;--accent:#fff36a;--ink:#000;--good:#c5ffb0;--bad:#ffd1b2}button,a{touch-action:manipulation}button{font:inherit;color:inherit;background:var(--card);border:1px solid var(--line);border-radius:12px;padding:10px 16px;cursor:pointer;min-height:46px;transition:background .15s}button:hover{border-color:var(--accent)}button:focus-visible,a:focus-visible{outline:3px solid var(--accent);outline-offset:4px}button:disabled{cursor:default;opacity:.55}a{color:var(--accent);text-underline-offset:4px}.app{max-width:1800px;margin:auto;padding:18px 28px 10px}header{display:flex;align-items:center;justify-content:space-between;gap:20px;margin-bottom:16px}.brand{display:flex;align-items:center;gap:12px}.brand-icon{background:var(--accent);color:var(--ink);font-size:38px;border-radius:14px;line-height:52px;width:52px;text-align:center}.brand strong{font-size:28px;display:block;letter-spacing:3px}.brand span:not(.brand-icon){display:block;font-size:16px;color:var(--muted)}.tools{display:flex;gap:8px}.tools button{font-size:17px}nav{display:flex;gap:12px;margin-bottom:20px}nav button{flex:1;text-align:left;padding:12px 20px;display:flex;align-items:baseline;gap:18px;background:transparent}nav b{font-size:24px}nav span{font-size:17px;color:var(--muted)}nav .active{background:var(--accent);color:var(--ink);border-color:var(--accent)}nav .active span{color:var(--ink)}main{display:grid;grid-template-columns:minmax(0,1fr) minmax(510px,1.06fr);gap:24px;min-height:475px}.scene{background:var(--panel);border:1px solid var(--line);border-radius:20px;overflow:hidden;display:flex;flex-direction:column}.scene img{width:100%;aspect-ratio:3/2;object-fit:contain;background:#254149;display:block;max-height:340px}.scene-caption{padding:15px 20px}.eyebrow{color:var(--accent);font-size:16px;letter-spacing:2px;font-weight:bold;margin:0 0 7px}.scene h2{font-size:26px;margin:0 0 8px;line-height:1.4}.scene p{margin:5px 0}.scene .facts{display:flex;gap:8px;flex-wrap:wrap;margin-top:12px}.chip{background:var(--card);border-radius:8px;padding:4px 10px;font-size:18px}.work{display:flex;flex-direction:column;min-width:0}.progress{display:flex;gap:8px;align-items:center;margin-bottom:12px;color:var(--muted);font-size:16px}.progress i{display:block;height:5px;flex:1;background:var(--line);border-radius:8px}.progress i.done{background:var(--accent)}.question{margin:0 0 14px;font-size:28px;line-height:1.4}.sub{margin:-5px 0 14px;color:var(--muted);font-size:18px}.options{display:grid;gap:10px}.option{text-align:left;display:flex;align-items:center;gap:12px;background:var(--panel);font-size:21px;padding:13px 16px}.option .letter{display:grid;place-items:center;width:32px;height:32px;flex:0 0 32px;border:1px solid var(--line);border-radius:50%;font-size:16px}.option.chosen{border:2px solid var(--accent)}.feedback{border-left:4px solid var(--accent);background:var(--panel);padding:12px 16px;margin-top:14px;font-size:20px}.feedback.bad{border-color:var(--bad)}.feedback strong{color:var(--good);display:block}.feedback.bad strong{color:var(--bad)}.next-row{display:flex;justify-content:space-between;align-items:center;gap:12px;margin-top:auto;padding-top:15px}.next{background:var(--accent);color:var(--ink);font-weight:bold;border-color:var(--accent)}.back{font-size:17px}.hint{color:var(--muted);font-size:16px}.med-tabs,.branch-tabs{display:flex;gap:8px;margin-bottom:12px}.med-tabs button{flex:1;padding:7px 10px}.med-tabs button.active,.branch-tabs button.active{border:2px solid var(--accent);color:var(--accent)}.package{border:1px solid var(--line);border-radius:15px;background:var(--panel);overflow:hidden;margin-bottom:12px}.package-title{background:var(--card);display:flex;justify-content:space-between;align-items:center;padding:9px 15px;font-size:21px}.package-title small{font-size:15px;color:var(--muted)}.package dl{margin:0;padding:10px 15px;display:grid;grid-template-columns:100px 1fr;gap:5px;font-size:18px}.package dt{color:var(--muted)}.package dd{margin:0}.classify{display:flex;gap:8px;flex-wrap:wrap}.classify button{font-size:18px;padding:8px 12px}.classify button.selected{background:var(--accent);color:var(--ink)}.callout{background:var(--card);padding:14px 17px;border-radius:12px;margin-bottom:12px;font-size:20px}.summary-list{list-style:none;padding:0;margin:0;display:grid;gap:12px}.summary-list li{background:var(--panel);border-radius:12px;padding:13px 16px}.summary-list b{color:var(--accent)}footer{display:flex;align-items:center;gap:20px;flex-wrap:wrap;margin-top:17px;color:var(--muted);font-size:15px}footer button{padding:4px 10px;font-size:15px;min-height:36px;background:transparent}.version{margin-left:auto}dialog{width:min(920px,94vw);max-height:88vh;border:1px solid var(--line);border-radius:20px;background:var(--bg);color:var(--text);padding:0}dialog::backdrop{background:#000b}.dialog-head{display:flex;justify-content:space-between;align-items:center;padding:18px 24px;border-bottom:1px solid var(--line);position:sticky;top:0;background:var(--bg)}.dialog-head h2{margin:0;font-size:25px}.dialog-body{padding:8px 26px 24px;font-size:18px}.dialog-body h3{color:var(--accent)}.dialog-body li{margin-bottom:12px}@media(min-width:1550px){.scene img{max-height:440px}.question{font-size:32px}.option{font-size:24px}.scene h2{font-size:30px}.package dl{font-size:21px}.package-title{font-size:24px}main{min-height:570px}}@media(max-width:1100px){.app{padding:14px 18px}main{grid-template-columns:minmax(0,.85fr) minmax(430px,1fr);gap:18px}.scene img{max-height:300px}.scene-caption{padding:13px}.question{font-size:25px}nav span{display:none}}@media(max-width:800px){header{align-items:flex-start;flex-wrap:wrap;gap:12px}.tools{width:100%}.tools button{flex:1}.brand strong{font-size:25px}nav{gap:8px}nav button{font-size:16px;padding:10px;gap:8px}nav b{font-size:20px}main{grid-template-columns:1fr;gap:18px}.scene img{max-height:280px}.scene-caption{padding:14px 18px}.scene h2{font-size:24px}.scene p{font-size:19px}.work{min-height:390px}footer{gap:10px}.version{margin-left:0}.question{font-size:26px}.option{font-size:20px}.app{padding:14px}.package dl{grid-template-columns:90px 1fr}.next-row{padding-top:18px}.branch-tabs button{font-size:18px}}
/* Laptop classroom layout: remove spacing, preserve readable text and whole images. */
@media(min-width:801px) and (max-height:850px){
 .app{padding:10px 24px 8px}header{margin-bottom:10px}.brand strong{font-size:26px}.brand-icon{line-height:48px;width:48px}nav{margin-bottom:12px}nav button{padding:8px 16px}main{min-height:460px}.scene img{max-height:270px}.scene-caption{padding:12px 18px}.scene h2{font-size:25px}.progress{margin-bottom:8px}.question{margin-bottom:10px}.sub{margin:-3px 0 10px}.med-tabs,.branch-tabs{margin-bottom:8px}.package{margin-bottom:8px}.package-title{padding:7px 14px}.package dl{padding:8px 14px;gap:3px;line-height:1.4}.feedback{margin-top:10px;padding:9px 13px}.next-row{padding-top:10px}.options{gap:8px}.option{padding:10px 14px}footer{margin-top:12px}.classify button{padding:7px 10px;min-height:44px}
}