:root{--ink:#1f2328;--muted:#59636e;--line:#d0d7de;--accent:#217346;--accent-ink:#fff;--bad:#b42318;--good:#1a7f37;--bg:#fff;--panel:#f6f8fa}
*{box-sizing:border-box}body{margin:0;font-family:system-ui,-apple-system,"Segoe UI",Roboto,sans-serif;color:var(--ink);background:var(--bg);line-height:1.5}
header{border-bottom:1px solid var(--line);background:var(--panel)}header .in{max-width:44rem;margin:0 auto;padding:.7rem 1rem;display:flex;align-items:center;gap:1rem;flex-wrap:wrap}
header .brand{font-weight:700;text-decoration:none;color:var(--ink);font-size:1.05rem}header .brand code{color:var(--accent)}
header nav{display:flex;gap:.9rem;margin-left:auto;align-items:center}header nav a,header nav button{color:var(--muted);text-decoration:none;background:none;border:0;font:inherit;cursor:pointer;padding:0}
header nav a:hover,header nav button:hover{color:var(--ink)}
main{max-width:44rem;margin:0 auto;padding:1.5rem 1rem 4rem}h1{font-size:1.5rem;margin:.2rem 0 1rem}h2{font-size:1.1rem;margin:1.6rem 0 .5rem}
p{margin:.6rem 0}.muted{color:var(--muted)}code{background:var(--panel);padding:.1em .3em;border-radius:4px;font-size:.95em}
pre{background:var(--panel);padding:.8rem;border-radius:6px;overflow-x:auto}
.card{border:1px solid var(--line);border-radius:8px;padding:1rem 1.1rem;margin:1rem 0;background:#fff}
label{display:block;font-weight:600;margin:.9rem 0 .3rem}input[type=text],input[type=email]{width:100%;padding:.55rem .65rem;border:1px solid var(--line);border-radius:6px;font:inherit}
.btn{display:inline-block;background:var(--accent);color:var(--accent-ink);border:0;border-radius:6px;padding:.55rem 1rem;font:inherit;font-weight:600;cursor:pointer;text-decoration:none}
.btn.secondary{background:#fff;color:var(--ink);border:1px solid var(--line)}.btn:hover{filter:brightness(.95)}
.q{margin:1rem 0}.q .t{font-weight:600}.hint{color:var(--muted);font-size:.9rem}
table{border-collapse:collapse;width:100%;margin:.5rem 0}th,td{text-align:left;padding:.45rem .5rem;border-bottom:1px solid var(--line)}th{font-size:.85rem;color:var(--muted);text-transform:uppercase;letter-spacing:.03em}
.ok{color:var(--good);font-weight:700}.no{color:var(--bad);font-weight:700}.big{font-size:2rem;font-weight:700}
.tag{display:inline-block;font-size:.75rem;padding:.1rem .45rem;border:1px solid var(--line);border-radius:999px;color:var(--muted);margin-left:.4rem;vertical-align:middle}
footer{max-width:44rem;margin:0 auto;padding:1rem;color:var(--muted);font-size:.85rem;border-top:1px solid var(--line)}
details.sol{margin:.5rem 0;border:1px solid var(--line);border-radius:6px;padding:.4rem .7rem}details.sol summary{cursor:pointer;font-weight:600}details.sol pre{white-space:pre-wrap;word-break:break-word;margin:.5rem 0 .2rem}
form.inline{display:inline}button.linkish{background:none;border:0;padding:0;color:var(--accent);font:inherit;cursor:pointer;text-decoration:underline}
td:first-child,th:first-child{white-space:nowrap}