:root{--paper:#f4f1e9;--card:#fffdf7;--ink:#242e29;--muted:#616a61;--line:#d8dbcf;--accent:#a44720;--good:#236047;--wash:#e9eee5;--bad:#8e3d28}*{box-sizing:border-box}body{margin:0;background:var(--paper);color:var(--ink);font-family:system-ui,"Microsoft YaHei",sans-serif;font-size:16px;line-height:1.7}button,input{font:inherit}button,a,input{touch-action:manipulation}button{min-height:46px;padding:10px 20px;cursor:pointer;border:1px solid transparent;border-radius:7px;background:var(--accent);color:white;font-weight:600}button:hover{filter:brightness(.96)}button:disabled{opacity:.55;cursor:default}button:focus-visible,a:focus-visible,input:focus-visible{outline:3px solid #cb854b;outline-offset:3px}a{color:var(--accent)}.top{height:82px;display:flex;align-items:center;justify-content:space-between;padding:0 5vw;border-bottom:1px solid var(--line);gap:16px}.brand{font-size:21px;font-weight:750;letter-spacing:2px;text-decoration:none;color:var(--ink)}.brand span{font-size:12px;letter-spacing:1px;margin-left:18px;color:var(--muted);font-weight:400}#save{font-size:12px;text-align:right;max-width:45%;color:var(--good)}.layout{max-width:1260px;margin:auto;display:grid;grid-template-columns:295px minmax(0,1fr);min-height:calc(100vh - 82px)}.side{padding:46px 30px 25px;border-right:1px solid var(--line);display:flex;flex-direction:column}.eyebrow{font-size:12px;letter-spacing:2px;color:var(--accent);font-weight:650;margin:0 0 14px}h1{font:600 30px/1.45 Georgia,"SimSun",serif;margin:0 0 20px}h2{font:600 29px/1.5 Georgia,"SimSun",serif;margin:0 0 16px}h3{font-size:19px;margin:10px 0}.muted{color:var(--muted)}nav{display:grid;gap:12px;margin-top:30px}.step{padding:10px 12px;color:var(--muted);border-left:2px solid var(--line);font-size:14px}.step.active{color:var(--accent);border-color:var(--accent);background:#a4472009}.step b{margin-right:12px;font-variant-numeric:tabular-nums}.side-bottom{margin-top:auto;padding-top:50px;font-size:12px;color:var(--muted)}.text-btn{padding:6px 0;background:transparent;color:var(--muted);font-size:13px;text-decoration:underline;min-height:44px}main{padding:46px clamp(20px,4vw,56px);min-width:0;outline:none}p{margin:0 0 18px}.card{background:var(--card);border:1px solid var(--line);border-radius:10px;padding:26px;margin:20px 0}.hero{background:var(--card);border:1px solid var(--line);padding:30px;border-radius:10px}.hero .equation{font-size:clamp(27px,4vw,40px);font-family:Georgia,"SimSun",serif;margin:25px 0}.tag{display:inline-block;padding:4px 10px;background:var(--wash);font-size:12px;color:var(--good);border-radius:4px;margin:3px 5px 5px 0}.grid{display:grid;grid-template-columns:1fr 1fr;gap:12px}.tile{background:var(--card);border:1px solid var(--line);padding:17px;border-radius:8px}.tile p{font-size:13px;color:var(--muted);margin:7px 0 0}.actions{display:flex;gap:12px;flex-wrap:wrap;margin-top:24px}.secondary{background:transparent;border-color:var(--line);color:var(--ink)}.question{font-size:clamp(26px,4vw,38px);font-family:Georgia,"SimSun",serif;line-height:1.5;overflow-wrap:anywhere;margin:28px 0}.answer-row{display:flex;gap:12px;flex-wrap:wrap}.answer-row input{width:180px;max-width:100%;border:1px solid #969f92;border-radius:6px;background:white;padding:12px 14px;min-height:49px}.hint,.small{font-size:13px;color:var(--muted)}.feedback{border-left:3px solid var(--good);background:var(--wash);padding:16px 18px;margin-top:20px}.feedback.wrong{border-color:var(--bad);background:#f7eae2}.feedback p:last-child{margin:0}.progress-track{height:4px;background:var(--line);margin:20px 0 28px;border-radius:3px}.progress-track span{height:100%;display:block;background:var(--accent)}.result-row{padding:17px 0;border-bottom:1px solid var(--line);display:flex;justify-content:space-between;align-items:center;gap:14px}.result-row small{display:block;color:var(--muted);font-size:12px}.result-row strong{font-size:15px}.pill{font-size:12px;padding:3px 9px;background:var(--wash);border-radius:4px;white-space:nowrap}.pill.need{color:var(--bad);background:#f5e5dc}.lesson-block{padding:18px 0;border-bottom:1px solid var(--line)}.lesson-block b{color:var(--accent);display:block;margin-bottom:7px}.formula{font:24px/1.7 Georgia,"SimSun",serif;padding:18px;background:var(--wash);text-align:center;border-radius:6px}.source{margin-top:20px;padding-top:14px;border-top:1px solid var(--line);font-size:12px;color:var(--muted)}.numberline{width:100%;height:120px;display:block}.controls{display:grid;grid-template-columns:1fr 1fr;gap:14px}.controls label{font-size:13px}.controls input{width:100%}.tiny-title{font-weight:600;font-size:14px}dialog{padding:0;width:min(1100px,96vw);height:92vh;border:1px solid var(--line);border-radius:10px;background:var(--card);overflow:hidden}dialog::backdrop{background:#12251cb0}.dialog-head{display:flex;justify-content:space-between;align-items:center;padding:10px 16px;gap:10px;border-bottom:1px solid var(--line)}dialog iframe{width:100%;height:calc(100% - 70px);border:0}.error{color:var(--bad);font-size:13px;margin-top:10px}ul{padding-left:22px}.summary-score{font:600 48px/1.2 Georgia,serif;color:var(--good);margin:22px 0}.notice{padding:16px;background:var(--wash);border-radius:6px;font-size:14px}details{font-size:13px;margin-top:24px}summary{cursor:pointer}pre{white-space:pre-wrap}.visually-hidden{position:absolute;width:1px;height:1px;overflow:hidden;clip-path:inset(50%)}
@media(max-width:800px){.layout{grid-template-columns:225px minmax(0,1fr)}.side{padding:30px 20px}h1{font-size:25px}main{padding:30px 23px}.brand span{display:none}.card,.hero{padding:20px}.grid{grid-template-columns:1fr}h2{font-size:25px}}
@media(max-width:560px){.top{height:65px;padding:0 20px}.layout{display:block}.side{border-right:0;border-bottom:1px solid var(--line);padding:24px 20px 15px}.side h1{font-size:25px;margin-bottom:10px}.side h1 br{display:none}.side>.muted{display:none}.side nav{display:flex;gap:7px;margin-top:12px}.step{flex:1;font-size:12px;padding:6px 2px;border-left:0;border-bottom:2px solid var(--line);text-align:center}.step b{display:none}.side-bottom{display:none}main{padding:25px 20px 45px}.card,.hero{padding:20px}.question{font-size:28px}.grid{grid-template-columns:1fr 1fr}.tile{padding:13px}.tile strong{font-size:14px}.controls{gap:10px}.dialog-head strong{font-size:13px}.result-row{align-items:flex-start}.answer-row input{width:155px}}