:root{color-scheme:light;--ink:#202f2a;--muted:#52635b;--green:#205e48;--paper:#f6f7f0;--white:#fff;--border:#dce4d9;--mint:#e3efdf}
*{box-sizing:border-box}body{margin:0;background:var(--paper);color:var(--ink);font-family:-apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei",sans-serif;line-height:1.6}
[hidden]{display:none!important}a{color:var(--green)}button,input{font:inherit}button{cursor:pointer}button:disabled{cursor:default;opacity:.5}button:focus-visible,a:focus-visible,input:focus-visible{outline:3px solid #bd651c;outline-offset:3px}
.wrap{width:min(960px,calc(100% - 36px));margin:auto}header{background:#fff;border-bottom:1px solid var(--border)}.top{min-height:66px;display:flex;align-items:center;justify-content:space-between}.brand{text-decoration:none;font-weight:800;color:var(--ink)}.brand span{display:inline-grid;place-items:center;width:34px;height:34px;background:var(--green);color:white;border-radius:10px;margin-right:6px}.edition,.eyebrow{color:var(--green);font-weight:700;font-size:.88rem}
.hero{margin:24px 0;padding:32px 38px;background:var(--mint);border-radius:25px}.hero h1{font-size:clamp(1.85rem,5vw,3.2rem);line-height:1.19;margin:5px 0 13px;letter-spacing:-.035em}.hero p{margin:0;color:var(--muted)}.hero .eyebrow{color:var(--green);margin-bottom:10px}.mobile{display:none}
nav{display:grid;grid-template-columns:repeat(5,1fr);gap:8px;margin-bottom:28px}.tab,.quiet,.primary{border-radius:12px;padding:10px 15px;border:1px solid var(--border);background:white;color:var(--ink);font-weight:700}.tab[aria-current=true],.primary{background:var(--green);color:white;border-color:var(--green)}.tab:hover,.quiet:hover{border-color:var(--green)}.primary:hover{background:#174936}.section-title{margin-bottom:5px}.muted{color:var(--muted);margin-top:0}.cards{display:grid;grid-template-columns:1.25fr 1fr;gap:14px}.card{background:white;border:1px solid var(--border);border-radius:20px;padding:22px 24px}.card h3{margin:8px 0}.label{font-size:.81rem;background:#edf3e7;color:#295944;padding:3px 10px;border-radius:12px;font-weight:700}.links{display:flex;gap:12px 18px;flex-wrap:wrap;margin-top:13px;font-size:.91rem}
.practice-head,.controls{display:flex;align-items:center;justify-content:space-between;gap:12px;margin:14px 0}progress{width:100%;height:12px;accent-color:var(--green);margin-bottom:14px}.option{width:100%;background:#fafbf7;border:1px solid var(--border);color:var(--ink);text-align:left;border-radius:12px;margin:4px 0;padding:10px 14px}.option:hover:not(:disabled){border-color:var(--green);background:#edf5ed}.option:disabled{opacity:1}.option.correct,.good{background:#e6f4e9;border-color:#a0c7ab;color:#164b2e}.option.incorrect,.bad{background:#fff0e6;border-color:#dcae94;color:#733312}.feedback{padding:13px 16px;border:1px solid;border-radius:12px;margin-top:14px}.feedback p{margin:4px 0}.jump{display:flex;flex-wrap:wrap;gap:6px}.jump button{min-width:39px;min-height:39px;border:1px solid var(--border);border-radius:8px;background:white;color:var(--ink)}.jump .done{background:var(--mint)}.jump [aria-current=true]{border:2px solid var(--green);font-weight:800}.part{display:block;margin:12px 0}.part input{display:block;width:100%;max-width:440px;padding:7px 10px;border:1px solid #96a99e;border-radius:8px;margin-top:4px}.diagram{display:block;width:min(100%,360px);height:auto;margin:10px 0}.diagram text{font-size:13px;fill:var(--ink)}.diagram path,.diagram line,.diagram ellipse{stroke:#668577;stroke-width:1.5;fill:none}.diagram circle{fill:var(--green)}footer{border-top:1px solid var(--border);margin-top:40px!important;padding:16px 0 24px;color:var(--muted);font-size:.86rem}footer span{float:right}
@media(max-width:600px){.wrap{width:calc(100% - 24px)}.hero{padding:24px;margin-top:16px}.mobile{display:initial}.cards{grid-template-columns:1fr}.card{padding:18px}.tab{padding:9px 4px}nav{gap:5px;margin-bottom:19px}footer span{float:none;display:block}}

.retry{margin-top:12px}