:root{color-scheme:dark;--bg:#0a101c;--panel:#152238;--line:#2a405e;--ink:#e9f4ff;--muted:#8fa9c4;--accent:#82d7ff;--btn:#167eae;--good:#9df6c8;--bad:#ffada1;--warn:#f0b35b}
*{box-sizing:border-box}
body{background:var(--bg);color:var(--ink);font:16px/1.55 system-ui,sans-serif;margin:0}
main{max-width:1040px;margin:0 auto;padding:8px 20px 24px}
a{color:var(--accent)}
h1{font-size:1.9rem;letter-spacing:.02em;margin:4px 0 10px}
h2{font-size:1.1rem;margin:0 0 10px;color:var(--accent)}
h2.section{margin:26px 0 0}
h3{font-size:.95rem;color:#a9c4de;margin:16px 0 8px}
h4{margin:0 0 6px;font-size:.9rem;color:#a9c4de}

/* header + nav */
header.site{border-bottom:1px solid var(--line);background:#0c1424;padding:12px 20px;display:flex;flex-wrap:wrap;gap:12px 28px;align-items:center}
.brand{display:flex;flex-direction:column;text-decoration:none;color:var(--ink)}
.brand .sub{color:#7c9bbb;font-size:.7rem;letter-spacing:.15em}
.brand .name{font-weight:800;letter-spacing:.06em}
nav.top{flex:1;display:flex;flex-wrap:wrap;gap:10px 20px;align-items:center;justify-content:space-between}
nav.top .links{display:flex;flex-wrap:wrap;gap:4px}
nav.top .links a{color:#c9d9ea;text-decoration:none;padding:6px 12px;border-radius:8px;font-size:.92rem}
nav.top .links a:hover{background:#16243a}
nav.top .links a.active{background:var(--panel);color:var(--accent);border:1px solid var(--line)}
nav.top .who{display:flex;gap:10px;align-items:center;color:var(--muted);font-size:.88rem}
#nav-score{color:var(--good);font-weight:700}

/* panels */
article{background:var(--panel);border:1px solid var(--line);border-radius:15px;padding:22px 24px;margin:18px 0}
article.narrow{max-width:560px;margin-left:auto;margin-right:auto}
article.scope{border-left:4px solid var(--warn)}
.challenge-head .eyebrow,.eyebrow{color:var(--warn);font-size:.78rem;letter-spacing:.14em;text-transform:uppercase;font-weight:700}
.head-row{display:flex;flex-wrap:wrap;gap:12px;align-items:center;justify-content:space-between}
.head-row p{margin:0}
.grid2{display:grid;grid-template-columns:1fr 1fr;gap:18px}
.grid2 article{margin-bottom:0}
.cols{display:grid;grid-template-columns:200px 1fr;gap:18px}
@media(max-width:700px){.grid2,.cols{grid-template-columns:1fr}}

/* cards */
.cards{display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:18px;margin-top:12px}
.card{display:block;background:var(--panel);border:1px solid var(--line);border-radius:15px;padding:20px;color:var(--ink);text-decoration:none;transition:border-color .15s,transform .15s}
.card:hover{border-color:var(--accent);transform:translateY(-2px)}
.card.solved{border-color:#3d7a5b}
.card h3{font-size:1.15rem;color:var(--ink);margin:6px 0}
.card p{color:#c9d9ea;font-size:.92rem}
.card .status{font-size:.88rem;color:var(--muted);font-weight:600}

/* forms + buttons */
button,a.button{display:inline-block;border:1px solid #68caff;background:var(--btn);color:white;border-radius:10px;padding:9px 16px;font:inherit;font-weight:700;cursor:pointer;text-decoration:none}
button:disabled{opacity:.5;cursor:default}
.alt{background:transparent}
.small{padding:5px 10px;font-size:.85rem}
input,select,textarea{background:#07121e;color:var(--ink);border:1px solid var(--line);border-radius:8px;padding:9px;font:inherit;width:100%}
textarea{font-family:ui-monospace,monospace;font-size:.9rem;margin-bottom:10px}
label{display:block;margin:12px 0}
label input,label select{display:block;margin-top:4px}
label small{display:block;color:var(--muted);font-size:.8rem;margin-top:3px}
label.choice{display:flex;gap:10px;align-items:flex-start;margin:6px 0;cursor:pointer}
label.choice input{width:auto;margin:5px 0 0}
label.rules{font-size:.88rem;color:#c9d9ea;margin:18px 0}
fieldset{border:1px solid var(--line);border-radius:10px;padding:8px 14px 10px;margin:14px 0}
legend{padding:0 6px;color:#c9d9ea}
.req{color:var(--warn);font-size:.75rem;text-transform:uppercase;letter-spacing:.08em;margin-left:6px}

/* content */
.plain{list-style:none;padding:0;margin:0}
.plain li{margin:4px 0}
.messages li{display:grid;grid-template-columns:110px 1fr;gap:10px;padding:6px 0;border-bottom:1px solid #1f3149}
.messages li b{color:var(--accent)}
.messages li.bad{display:block}
table{border-collapse:collapse;width:100%;font-size:.9rem}
th,td{text-align:left;padding:7px 9px;border-bottom:1px solid var(--line);vertical-align:top}
th{color:#a9c4de;font-weight:600}
.table-wrap{overflow-x:auto}
code{padding:2px 6px;background:#0a1525;border-radius:4px;font-size:.9em}
pre{white-space:pre-wrap;word-break:break-word;background:#07121e;border:1px solid #243c54;padding:12px;border-radius:10px;margin:6px 0;font-size:.85rem}
pre.log{border-color:#3d5f3d;color:#bfe8c8}
.doc{margin:14px 0}
ol.hints li{margin:6px 0}
.facts{display:grid;grid-template-columns:auto 1fr;gap:6px 16px;margin:0}
.facts dt{color:var(--muted)}
.facts dd{margin:0}
.big{font-size:2rem;font-weight:800;margin:0}
.stats{display:flex;flex-wrap:wrap;gap:14px}
.stat{background:#0f1a2c;border:1px solid var(--line);border-radius:12px;padding:12px 18px;min-width:140px}
.stat .big{font-size:1.6rem}
.muted{color:var(--muted);font-size:.88rem}
.bad{color:var(--bad)}
.good{color:var(--good)}
footer{color:#94b1cb;font-size:.82rem;text-align:center;padding:20px 20px 36px}