:root{
  --bg:#10151F; --surface-1:#172030; --surface-2:#212C40;
  --accent:#5FB8B0; --accent-deep:#4aa39b; --accent-2:#93A8CC;
  --ink:#ECEEF3; --muted:#9BA6B8; --gold:#E9B949; --correct:#4ade80;
  --line:rgba(95,184,176,.15); --maxw:800px;
}
*{box-sizing:border-box}
body{margin:0;background:var(--bg);color:var(--ink);
  font-family:"Inter",-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,sans-serif;
  line-height:1.65;-webkit-font-smoothing:antialiased}
h1,h2,h3,.brand,.n{font-family:"Space Grotesk","Inter",sans-serif}
a{color:var(--accent);text-decoration:none}
a:hover{text-decoration:underline}
a:focus-visible{outline:2px solid var(--accent);outline-offset:3px;border-radius:3px}
.wrap{max-width:var(--maxw);margin:0 auto;padding:0 20px}
nav{position:sticky;top:0;z-index:50;backdrop-filter:blur(12px);
  background:rgba(16,21,31,.8);border-bottom:1px solid var(--line)}
nav .wrap{display:flex;align-items:center;justify-content:space-between;height:62px;gap:14px}
.brand{font-weight:700;letter-spacing:-.02em;color:var(--ink)}
.btn{display:inline-flex;align-items:center;justify-content:center;font-weight:800;
  border-radius:999px;padding:11px 22px;background:var(--accent-deep);color:var(--bg);
  border:0;cursor:pointer;text-decoration:none}
.btn:hover{background:var(--accent);text-decoration:none}
.btn:active{transform:scale(.97)}
.btn.play{background:linear-gradient(135deg,#f5e0a8,#e9b949 45%,#d4a32f);color:#241c02}
.btn.ghost{background:transparent;border:1px solid var(--line);color:var(--ink)}
.btn.ghost:hover{background:var(--surface-1)}
main{padding:34px 0 72px}
.crumbs{font-size:.85rem;color:var(--muted);margin-bottom:14px}
.crumbs span{margin:0 4px}
h1{font-size:clamp(1.75rem,5vw,2.5rem);line-height:1.12;letter-spacing:-.03em;margin:0 0 14px;
  text-wrap:balance}
h2{font-size:1.3rem;letter-spacing:-.02em;margin:44px 0 14px;text-wrap:balance}
.intro{color:var(--muted);font-size:1.05rem;margin:0 0 8px}
.listhead{border-top:1px solid var(--line);padding-top:30px}
.muted{color:var(--muted)}
.qalist{list-style:none;margin:0;padding:0;display:flex;flex-direction:column;gap:14px}
.qa{background:var(--surface-1);border:1px solid var(--line);border-radius:12px;padding:16px 18px}
.qa .q{margin:0 0 10px;font-weight:600;display:flex;gap:11px;align-items:baseline}
.qa .n{color:var(--accent-2);font-size:.85rem;font-weight:700;min-width:1.6em;
  font-variant-numeric:tabular-nums}
.qa .a{margin:0;color:var(--correct);font-weight:600;display:flex;gap:9px;align-items:baseline;
  flex-wrap:wrap}
.qa .lbl{font-size:.66rem;letter-spacing:.14em;text-transform:uppercase;color:var(--muted);
  font-weight:700}
.qa .why{margin:8px 0 0;color:var(--muted);font-size:.94rem}
.siblings ul{list-style:none;margin:0;padding:0;display:grid;
  grid-template-columns:repeat(auto-fill,minmax(230px,1fr));gap:10px}
.siblings a{display:flex;justify-content:space-between;align-items:center;gap:10px;
  background:var(--surface-1);border:1px solid var(--line);border-radius:10px;
  padding:13px 15px;color:var(--ink)}
.siblings a:hover{background:var(--surface-2);text-decoration:none}
.siblings em{font-style:normal;color:var(--muted);font-size:.85rem;
  font-variant-numeric:tabular-nums}
.crosslink{margin-top:30px;background:var(--surface-1);border:1px solid var(--line);
  border-left:3px solid var(--accent);border-radius:0 10px 10px 0;padding:14px 17px}
.crosslink p{margin:0;color:var(--muted)}
.crosslink strong{color:var(--ink);margin-right:6px}
.cta{margin-top:48px;background:var(--surface-1);border:1px solid var(--line);
  border-radius:14px;padding:26px 24px}
.cta h2{margin:0 0 8px;font-size:1.2rem}
.cta p{margin:0 0 14px;color:var(--muted)}
.ctarow{display:flex;gap:11px;flex-wrap:wrap;margin:0}
footer{border-top:1px solid var(--line);padding:22px 0;color:var(--muted);font-size:.88rem}
/* ---- quiz ---- */
.quiz{margin:22px 0 0}
.quizcard{background:var(--surface-1);border:1px solid var(--line);border-radius:14px;
  padding:20px 20px 22px}
.quizhead{display:flex;justify-content:space-between;align-items:baseline;gap:12px;
  font-size:.8rem;color:var(--muted);margin-bottom:12px;font-variant-numeric:tabular-nums}
.quizq{font-size:1.08rem;font-weight:600;margin:0 0 14px;text-wrap:balance}
.opts{display:flex;flex-direction:column;gap:8px}
.opt{text-align:left;background:var(--surface-2);border:1px solid transparent;color:var(--ink);
  border-radius:10px;padding:12px 14px;cursor:pointer;font:inherit;font-size:.97rem;
  transition:background .12s ease}
.opt:hover:not(:disabled){background:#2a3752}
.opt:disabled{cursor:default}
.opt.right{border-color:var(--correct);color:var(--correct)}
.opt.wrong{border-color:#e07a74;color:#e0a09b}
.reveal{margin-top:4px}
.answer{margin:14px 0 0;color:var(--correct);font-weight:600}
.explain{margin:8px 0 0;color:var(--muted);font-size:.94rem}
.quizfoot{display:flex;gap:10px;flex-wrap:wrap;margin-top:16px}
.score{font-size:1.15rem;font-weight:700;font-family:"Space Grotesk",sans-serif}
@media (max-width:520px){main{padding-top:24px}.cta{padding:20px 17px}}
@media (prefers-reduced-motion:reduce){*{transition:none!important;animation:none!important}}