:root{--bg:#FCFCFB;--card:#F1EFEA;--note:#E9E6DF;--ink:#1A1714;--dim:#55504A;--line:#CFC8BD;--ok:#15803D;--bad:#B91C1C}
*{box-sizing:border-box}
body{margin:0;background:var(--bg);color:var(--ink);font:16px/1.55 system-ui,-apple-system,"Segoe UI",Roboto,Arial,sans-serif}
a{color:#1F6FD0}
.wrap{max-width:1080px;margin:0 auto;padding:16px}
.top{display:flex;align-items:center;justify-content:space-between;gap:12px;flex-wrap:wrap;padding:8px 0 14px;border-bottom:1px solid var(--line)}
.brand{display:flex;gap:12px;align-items:center}
.mark{width:44px;height:44px;border-radius:10px;background:#7C3AED;color:#fff;font-weight:800;display:grid;place-items:center;flex:none}
h1{font-size:26px;margin:0;line-height:1.2}
.brand p{margin:2px 0 0;color:var(--dim);font-size:14px}
.home-link{font-size:14px;text-decoration:none;color:var(--dim)}
.toc{display:flex;flex-wrap:wrap;gap:6px;margin:14px 0 4px}
.toc a{font-size:13px;text-decoration:none;color:var(--ink);background:var(--card);padding:5px 10px;border-radius:14px}
section{margin:34px 0}
h2{font-size:22px;margin:0 0 8px}
.lead{color:var(--dim);margin:0 0 16px;max-width:780px}
.kinds{display:grid;grid-template-columns:repeat(4,1fr);gap:12px}
.kcard{background:#fff;border:1px solid var(--line);border-top:5px solid var(--c);border-radius:10px;padding:14px}
.kname{font-weight:800;color:var(--c);font-size:17px;margin-bottom:6px}
.kcard p{margin:0 0 8px;font-size:14px}
.kcard .ksign{background:var(--card);padding:8px;border-radius:6px;font-size:13px;margin:0}
.svgbox{background:#fff;border:1px solid var(--line);border-radius:10px;padding:10px;overflow:hidden}
.svgbox.small{max-width:560px;margin:12px 0}
svg.tree{width:100%;height:auto;display:block}
svg .tl{font-size:12.5px}
svg .tk{font-size:10px;font-weight:800;letter-spacing:.06em}
svg .ts{font-size:11px}
.tablewrap{overflow-x:auto}
table.cmp{border-collapse:collapse;width:100%;background:#fff;font-size:14px;min-width:640px}
.cmp th,.cmp td{border-bottom:1px solid var(--line);padding:9px 10px;text-align:left;vertical-align:top}
.cmp thead th{font-size:15px}
.cmp tbody th{background:var(--card);width:14%}
.examples{display:grid;grid-template-columns:repeat(2,1fr);gap:14px}
.ex{background:#fff;border:1px solid var(--line);border-radius:10px;padding:14px}
.ex h3{margin:6px 0;font-size:18px}
.ex p{margin:0 0 10px;font-size:14px}
.ex .svgbox{border:none;padding:0}
.exhead{display:flex;justify-content:space-between;align-items:center}
.tag{color:#fff;font-size:12px;font-weight:700;padding:3px 9px;border-radius:12px}
.lesson{font-size:12px;color:var(--dim)}
.quiz{background:var(--card);border-radius:12px;padding:18px}
.prog{display:flex;align-items:center;gap:12px;font-size:14px;color:var(--dim);margin-bottom:12px}
.bar{flex:1;height:8px;background:#fff;border-radius:4px;overflow:hidden}
.bar i{display:block;height:100%;background:#7C3AED;width:0;transition:width .3s}
.qbox{background:#fff;border-radius:10px;padding:18px}
.qn{font-size:13px;color:var(--dim)}
.q{font-size:18px;font-weight:600;margin:6px 0 14px}
.choices{display:grid;grid-template-columns:repeat(4,1fr);gap:8px}
.ch{border:2px solid var(--c);background:#fff;color:var(--c);font-weight:700;font-size:15px;padding:12px 8px;border-radius:9px;cursor:pointer}
.ch:hover:not(:disabled){background:var(--c);color:#fff}
.opts{display:grid;gap:8px}
.opt{text-align:left;border:1px solid var(--line);background:#fff;padding:11px 12px;border-radius:9px;font-size:15px;cursor:pointer;color:var(--ink)}
.opt:hover:not(:disabled){border-color:#7C3AED}
.opt b{color:#7C3AED;margin-right:6px}
button:disabled{cursor:default}
.right{background:var(--ok)!important;color:#fff!important;border-color:var(--ok)!important}
.right b{color:#fff}
.wrong{background:var(--bad)!important;color:#fff!important;border-color:var(--bad)!important}
.wrong b{color:#fff}
.dim{opacity:.45}
.verdict{margin:14px 0 0;padding:11px 13px;border-radius:8px;font-size:15px}
.verdict.ok{background:#E7F4EC;border-left:4px solid var(--ok)}
.verdict.bad{background:#FBEAEA;border-left:4px solid var(--bad)}
.next{margin-top:14px;background:#1A1714;color:#fff;border:none;padding:11px 18px;border-radius:9px;font-size:15px;cursor:pointer}
.fin .big{font-size:40px;font-weight:800;color:#7C3AED}
.errs{font-size:14px;padding-left:18px}
.errs li{margin-bottom:8px}
.cta{background:#fff;border:1px solid var(--line);border-radius:12px;padding:18px}
.src{border-top:1px solid var(--line);margin-top:34px;padding-top:14px;font-size:13px;color:var(--dim)}
.src h3{font-size:15px;color:var(--ink)}
.ref{padding-left:2em;text-indent:-2em;margin:4px 0}
.disc{font-size:12px}
@media (max-width:820px){.kinds{grid-template-columns:1fr 1fr}.examples{grid-template-columns:1fr}.choices{grid-template-columns:1fr 1fr}}
@media (max-width:520px){.kinds{grid-template-columns:1fr}h1{font-size:21px}.q{font-size:16px}.quiz{padding:12px}.qbox{padding:12px}}