:root{--bg:#f6f1e7;--ink:#1d1b18;--muted:#6b645a;--red:#c0262d;--green:#1f6f4a;--card:#fff;--line:#e2d9c8;--accent:#c0262d}
*{box-sizing:border-box}
body{margin:0;background:var(--bg);color:var(--ink);font:17px/1.55 -apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,sans-serif}
main{max-width:760px;margin:0 auto;padding:20px 18px 80px}
header.hero{background:var(--green);color:#fff;padding:36px 18px 28px;text-align:center}
header.hero h1{margin:0;font-size:2.1em;letter-spacing:.5px}
header.hero .zh{font-size:1.3em;opacity:.9}
header.hero p{margin:.6em auto 0;max-width:560px;opacity:.92}
nav.toc{background:#fff;border:1px solid var(--line);border-radius:12px;padding:12px 16px;margin:20px 0}
nav.toc ol{margin:0;padding-left:1.3em;columns:2;column-gap:24px}
nav.toc a{color:var(--green);text-decoration:none}
section{margin-top:36px}
h2{font-size:1.35em;border-bottom:2px solid var(--line);padding-bottom:6px;margin-bottom:12px}
h2 .n{display:inline-block;background:var(--accent);color:#fff;border-radius:50%;width:1.6em;height:1.6em;text-align:center;line-height:1.6em;font-size:.8em;margin-right:8px;vertical-align:middle}
h3{font-size:1.05em;margin:18px 0 6px}
.box{background:#fff;border:1px solid var(--line);border-radius:12px;padding:12px 16px;margin:12px 0}
.tip{border-left:5px solid var(--green)}
.warn{border-left:5px solid var(--accent)}
.muted{color:var(--muted);font-size:.92em}
.hand{display:flex;flex-wrap:wrap;gap:5px;margin:6px 0 4px;align-items:center}
.c{display:inline-flex;flex-direction:column;justify-content:center;align-items:center;width:38px;height:54px;background:var(--card);border:1px solid #bbb;border-radius:6px;font-weight:700;font-size:15px;line-height:1.05;box-shadow:0 1px 2px rgba(0,0,0,.12);color:#111}
.c small{font-size:15px}
.c.r{color:var(--red)}
.c.w{background:#fff3c4;border-color:#d9a400}
.c.jr{color:var(--red);font-size:10px}
.c.jb{color:#111;font-size:10px}
.c.lv{outline:2px solid var(--green);outline-offset:1px}
.vs{font-weight:700;color:var(--muted);padding:0 6px}
.ok{color:var(--green);font-weight:700}
.no{color:var(--accent);font-weight:700}
table{border-collapse:collapse;width:100%;background:#fff;border-radius:10px;overflow:hidden;margin:10px 0}
td,th{border:1px solid var(--line);padding:8px 10px;text-align:left;vertical-align:top}
th{background:#efe7d6}
.ladder li{margin:4px 0}
.combo{display:grid;grid-template-columns:110px 1fr;gap:4px 12px;align-items:center;border-bottom:1px dashed var(--line);padding:8px 0}
.combo b{font-size:.95em}
.quiz .q{background:#fff;border:1px solid var(--line);border-radius:12px;padding:12px 16px;margin:12px 0}
.quiz button{font:inherit;padding:6px 14px;margin:6px 8px 0 0;border-radius:8px;border:1px solid var(--line);background:#faf7f0;cursor:pointer}
.quiz button.right{background:#d8f0e2;border-color:var(--green)}
.quiz button.wrong{background:#f8dcdc;border-color:var(--accent)}
.quiz .why{display:none;margin-top:8px;color:var(--muted)}
.quiz .q.done .why{display:block}
.seat{display:grid;grid-template-columns:1fr 1fr 1fr;grid-template-rows:auto auto auto;text-align:center;max-width:320px;margin:10px auto;gap:6px}
.seat div{padding:8px;border-radius:8px}
.seat .a{background:#d8f0e2}.seat .b{background:#f8dcdc}.seat .t{background:#e9e1cf;font-size:.85em;color:var(--muted)}
footer{margin-top:50px;color:var(--muted);font-size:.85em;text-align:center}
@media (max-width:520px){nav.toc ol{columns:1}.combo{grid-template-columns:1fr}}