/* FireFuelED Study Hub — shared stylesheet
   Professional study-material layout: sticky topic sidebar, readable measure,
   reference tables, algorithm flows, callouts, self-check quizzes. */

:root{
  --ink:#101622; --ink-soft:#54607a; --bg:#ffffff; --bg-alt:#f6f8fc; --line:#e7ebf3;
  --ember:#e8521f; --ember-deep:#c23d12; --ember-light:#ff7a3d; --teal:#0e8c84; --navy:#0a1020;
  --red:#c62828; --yellow:#b98900; --green:#2e7d32; --black:#333a46;
  --sans:'Inter',system-ui,-apple-system,'Segoe UI',Roboto,sans-serif;
  --display:'Space Grotesk',var(--sans);
  --radius:14px; --shadow:0 8px 26px rgba(16,22,34,.07);
}
*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth;scroll-padding-top:84px}
body{font-family:var(--sans);color:var(--ink);background:var(--bg);line-height:1.65;-webkit-font-smoothing:antialiased}
a{color:inherit;text-decoration:none}
.wrap{width:100%;max-width:1160px;margin:0 auto;padding:0 24px}

/* ---------- top nav (same pattern as site) ---------- */
nav.topnav{position:sticky;top:0;z-index:30;background:rgba(255,255,255,.88);backdrop-filter:blur(14px);border-bottom:1px solid var(--line)}
nav.topnav .wrap{display:flex;align-items:center;justify-content:space-between;height:64px;max-width:1160px}
.logo{font-family:var(--display);font-weight:700;font-size:19px;letter-spacing:-.3px;display:flex;align-items:center;gap:10px}
.logo .mark{width:26px;height:26px;flex-shrink:0}
.logo .brand-text span{color:var(--ember)}
.nav-links{display:flex;gap:26px;font-size:14.5px;font-weight:500;align-items:center}
.nav-links a{color:var(--ink-soft);transition:color .15s}
.nav-links a:hover{color:var(--ink)}
.nav-links a.active{color:var(--ember);font-weight:600}
.nav-cta{color:var(--ink)!important;font-weight:600}
.nav-burger{display:none;background:none;border:0;cursor:pointer;padding:10px 2px 10px 12px}
.nav-burger span{display:block;width:22px;height:2px;background:var(--ink);margin:5px 0;border-radius:2px;transition:transform .2s,opacity .2s}
.nav-burger.open span:nth-child(1){transform:translateY(7px) rotate(45deg)}
.nav-burger.open span:nth-child(2){opacity:0}
.nav-burger.open span:nth-child(3){transform:translateY(-7px) rotate(-45deg)}
.m-menu{display:none}
@media(max-width:760px){
  .nav-links{display:none}
  .nav-burger{display:block}
  .m-menu.open{display:block;position:absolute;top:100%;left:0;right:0;background:#fff;border-bottom:1px solid var(--line);box-shadow:0 18px 38px rgba(16,22,34,.14);padding:6px 22px 14px;z-index:29}
  .m-menu a{display:block;padding:12px 2px;font-size:15.5px;font-weight:500;color:var(--ink);border-bottom:1px solid rgba(16,22,34,.07)}
  .m-menu a:last-child{border-bottom:0}
  .m-menu .m-sub{font-size:11.5px;letter-spacing:1.2px;text-transform:uppercase;color:#8a93a6;padding:12px 2px 2px;font-weight:600}
}

/* ---------- study layout: sidebar + article ---------- */
.study-shell{display:grid;grid-template-columns:250px minmax(0,1fr);gap:48px;max-width:1160px;margin:0 auto;padding:36px 24px 90px}
@media(max-width:920px){.study-shell{grid-template-columns:1fr;gap:0;padding-top:20px}}

/* sidebar */
.side{position:sticky;top:84px;align-self:start;max-height:calc(100vh - 100px);overflow-y:auto;padding-right:6px}
.side::-webkit-scrollbar{width:4px}
.side::-webkit-scrollbar-thumb{background:var(--line);border-radius:4px}
.side-label{font-size:11px;font-weight:700;letter-spacing:1.6px;text-transform:uppercase;color:var(--ink-soft);margin:18px 0 8px;padding-left:12px}
.side-label:first-child{margin-top:0}
.side a.topic{display:flex;align-items:center;gap:9px;padding:8px 12px;border-radius:9px;font-size:14px;font-weight:500;color:var(--ink-soft);transition:background .12s,color .12s;line-height:1.35}
.side a.topic:hover{background:var(--bg-alt);color:var(--ink)}
.side a.topic.current{background:#fff0e9;color:var(--ember-deep);font-weight:600}
.side a.topic .t-num{font-family:var(--display);font-size:11.5px;font-weight:700;color:#aab3c7;width:18px;flex-shrink:0;text-align:right}
.side a.topic.current .t-num{color:var(--ember)}
.side .on-page{margin:6px 0 4px;border-left:2px solid var(--line);margin-left:21px}
.side .on-page a{display:block;padding:5px 0 5px 13px;font-size:13px;color:var(--ink-soft);border-left:2px solid transparent;margin-left:-2px;transition:color .12s,border-color .12s}
.side .on-page a:hover{color:var(--ink)}
.side .on-page a.here{color:var(--ember-deep);border-left-color:var(--ember);font-weight:600}
@media(max-width:920px){
  .side{position:static;max-height:none;margin-bottom:26px;padding:0}
  .side-desk{display:none}
  details.side-mobile{display:block;border:1px solid var(--line);border-radius:12px;background:var(--bg-alt)}
  details.side-mobile summary{list-style:none;cursor:pointer;display:flex;align-items:center;justify-content:space-between;padding:13px 16px;font-family:var(--display);font-weight:600;font-size:15px}
  details.side-mobile summary::-webkit-details-marker{display:none}
  details.side-mobile summary::after{content:"▾";color:var(--ink-soft);transition:transform .15s}
  details.side-mobile[open] summary::after{transform:rotate(180deg)}
  details.side-mobile .side-inner{padding:2px 10px 12px}
}
@media(min-width:921px){details.side-mobile{display:none}}

/* ---------- article ---------- */
article.study{max-width:760px;min-width:0}
.crumb{font-size:13px;color:var(--ink-soft);margin-bottom:14px}
.crumb a{color:var(--ink-soft)}
.crumb a:hover{color:var(--ember)}
.crumb .sep{margin:0 7px;color:#c3cad9}
.guide-tag{display:inline-flex;align-items:center;gap:7px;font-size:11.5px;font-weight:700;letter-spacing:1.4px;text-transform:uppercase;color:var(--ember);margin-bottom:10px}
article.study h1{font-family:var(--display);font-size:clamp(30px,4.6vw,42px);font-weight:700;letter-spacing:-1.1px;line-height:1.08;margin-bottom:14px}
.lede{font-size:17.5px;color:var(--ink-soft);max-width:62ch}
.meta-row{display:flex;flex-wrap:wrap;gap:8px;margin:20px 0 6px}
.chip{display:inline-flex;align-items:center;gap:6px;font-size:12.5px;font-weight:600;color:var(--ink-soft);background:var(--bg-alt);border:1px solid var(--line);border-radius:999px;padding:5px 13px}
.chip.hot{background:#fff0e9;border-color:#ffd9c7;color:var(--ember-deep)}

article.study section.sec{margin-top:52px}
article.study h2{font-family:var(--display);font-size:clamp(22px,3vw,27px);font-weight:700;letter-spacing:-.5px;line-height:1.2;padding-top:18px;border-top:1px solid var(--line);margin-bottom:14px}
article.study h2 .h-num{color:var(--ember);margin-right:8px;font-size:.8em;vertical-align:2px}
article.study h3{font-family:var(--display);font-size:18px;font-weight:600;letter-spacing:-.2px;margin:26px 0 8px}
article.study p{margin:0 0 14px;max-width:68ch}
article.study p b,article.study li b{color:var(--ink)}
article.study ul,article.study ol{margin:0 0 16px;padding-left:24px;max-width:66ch}
article.study li{margin-bottom:7px}
article.study li::marker{color:var(--ember);font-weight:600}

/* ---------- components ---------- */
/* key point / caution / mnemonic callouts */
.callout{border-radius:var(--radius);padding:16px 18px 16px 16px;margin:20px 0;display:flex;gap:13px;font-size:15px;line-height:1.6}
.callout .co-ic{flex-shrink:0;width:22px;height:22px;margin-top:2px}
.callout b.co-t{display:block;font-family:var(--display);font-size:13px;font-weight:700;letter-spacing:.8px;text-transform:uppercase;margin-bottom:4px}
.callout.key{background:#f0faf9;border:1px solid #c5e8e5}
.callout.key .co-ic,.callout.key b.co-t{color:var(--teal)}
.callout.warn{background:#fff6f2;border:1px solid #ffd9c7}
.callout.warn .co-ic,.callout.warn b.co-t{color:var(--ember-deep)}
.callout.mnem{background:#f7f5ff;border:1px solid #ddd6f5}
.callout.mnem .co-ic,.callout.mnem b.co-t{color:#5b4bc4}
.callout p:last-child{margin-bottom:0}

/* reference tables */
.tbl-wrap{overflow-x:auto;margin:20px 0;border:1px solid var(--line);border-radius:var(--radius);box-shadow:var(--shadow)}
table.ref{width:100%;border-collapse:collapse;font-size:14.5px;min-width:480px}
table.ref caption{caption-side:top;text-align:left;font-family:var(--display);font-weight:600;font-size:14px;padding:13px 16px;background:var(--bg-alt);border-bottom:1px solid var(--line);color:var(--ink)}
table.ref th{font-family:var(--display);font-size:12px;font-weight:700;letter-spacing:.8px;text-transform:uppercase;color:var(--ink-soft);text-align:left;padding:11px 16px;background:var(--bg-alt);border-bottom:1px solid var(--line)}
table.ref td{padding:11px 16px;border-bottom:1px solid var(--line);vertical-align:top}
table.ref tr:last-child td{border-bottom:0}
table.ref tbody tr:nth-child(even){background:#fafbfe}
table.ref td b{font-weight:600}

/* triage color dots (START etc.) */
.dot{display:inline-block;width:10px;height:10px;border-radius:50%;margin-right:7px;vertical-align:0}
.dot.red{background:#e53935}.dot.yellow{background:#fbc02d}.dot.green{background:#43a047}.dot.black{background:#37474f}

/* algorithm / step flow */
.algo{margin:22px 0;border:1px solid var(--line);border-radius:var(--radius);overflow:hidden;box-shadow:var(--shadow)}
.algo .algo-t{font-family:var(--display);font-weight:600;font-size:14px;padding:13px 18px;background:var(--navy);color:#fff;letter-spacing:.2px}
.algo .step{display:flex;gap:14px;padding:15px 18px;border-bottom:1px solid var(--line);font-size:15px;line-height:1.55}
.algo .step:last-child{border-bottom:0}
.algo .s-n{flex-shrink:0;width:26px;height:26px;border-radius:50%;background:#fff0e9;color:var(--ember-deep);font-family:var(--display);font-weight:700;font-size:13px;display:flex;align-items:center;justify-content:center;margin-top:1px}
.algo .step b{color:var(--ink)}
.algo .step .then{display:block;margin-top:5px;font-size:13.5px;color:var(--ink-soft)}
.algo .step .then b{font-weight:600}

/* decision fork inside a step */
.fork{margin-top:8px;display:grid;gap:6px}
.fork span{display:flex;gap:8px;align-items:baseline;font-size:13.5px;color:var(--ink-soft)}
.fork .f-if{flex-shrink:0;font-family:var(--display);font-weight:700;font-size:11px;letter-spacing:.6px;text-transform:uppercase;padding:2px 9px;border-radius:999px;margin-top:1px}
.fork .f-if.bad{background:#fdecea;color:var(--red)}
.fork .f-if.ok{background:#eaf6eb;color:var(--green)}
.fork .f-if.mid{background:#fef7e0;color:var(--yellow)}

/* term/definition list */
.terms{margin:20px 0;display:grid;gap:0;border:1px solid var(--line);border-radius:var(--radius);overflow:hidden}
.terms>div{display:grid;grid-template-columns:190px 1fr;border-bottom:1px solid var(--line)}
.terms>div:last-child{border-bottom:0}
.terms>div:nth-child(even){background:#fafbfe}
.terms dt{font-weight:600;font-size:14.5px;padding:11px 16px;background:var(--bg-alt);border-right:1px solid var(--line)}
.terms dd{font-size:14.5px;padding:11px 16px;color:var(--ink-soft)}
@media(max-width:560px){.terms>div{grid-template-columns:1fr}.terms dt{border-right:0;border-bottom:1px dashed var(--line);padding-bottom:7px}.terms dd{padding-top:7px}}

/* self-check quiz */
.quiz{margin:22px 0;border:1px solid var(--line);border-radius:var(--radius);overflow:hidden;box-shadow:var(--shadow)}
.quiz .q-head{font-family:var(--display);font-weight:600;font-size:14px;padding:13px 18px;background:var(--bg-alt);border-bottom:1px solid var(--line);display:flex;align-items:center;gap:9px}
.quiz .q-head svg{width:17px;height:17px;color:var(--ember)}
details.q{border-bottom:1px solid var(--line)}
details.q:last-child{border-bottom:0}
details.q summary{list-style:none;cursor:pointer;padding:14px 18px;font-size:15px;font-weight:500;display:flex;gap:12px;transition:background .12s}
details.q summary::-webkit-details-marker{display:none}
details.q summary:hover{background:#fafbfe}
details.q summary .q-n{flex-shrink:0;font-family:var(--display);font-weight:700;font-size:12.5px;color:var(--ember);margin-top:2px}
details.q .q-a{padding:2px 18px 16px 44px;font-size:14.5px;color:var(--ink-soft);line-height:1.6}
details.q .q-a b{color:var(--ink)}
details.q[open] summary{background:#fafbfe}

/* drill-it game CTA */
.drill{margin:30px 0 8px;border-radius:18px;background:radial-gradient(480px 300px at 88% -20%, rgba(232,82,31,.25), transparent 60%),linear-gradient(160deg,#13203b,var(--navy));color:#fff;padding:26px 26px;display:flex;align-items:center;gap:20px;flex-wrap:wrap;border:1px solid rgba(255,255,255,.08)}
.drill .d-ic{width:56px;height:56px;border-radius:14px;overflow:hidden;flex-shrink:0;box-shadow:0 6px 18px rgba(0,0,0,.4)}
.drill .d-ic img{width:100%;height:100%;object-fit:cover;display:block}
.drill .d-tx{flex:1;min-width:220px}
.drill .d-k{font-size:11px;font-weight:700;letter-spacing:1.6px;text-transform:uppercase;color:var(--ember-light)}
.drill b.d-t{display:block;font-family:var(--display);font-size:19px;font-weight:700;margin:3px 0 4px;letter-spacing:-.3px}
.drill .d-s{font-size:14px;color:#aeb7cd;line-height:1.5}
.drill a.d-btn{display:inline-flex;align-items:center;gap:8px;background:var(--ember);color:#fff;font-weight:600;font-size:14.5px;padding:12px 22px;border-radius:11px;transition:transform .15s,background .15s;white-space:nowrap}
.drill a.d-btn:hover{background:var(--ember-deep);transform:translateY(-2px)}

/* prev / next pagination */
.pager{display:grid;grid-template-columns:1fr 1fr;gap:14px;margin-top:56px;padding-top:26px;border-top:1px solid var(--line)}
.pager a{border:1px solid var(--line);border-radius:var(--radius);padding:15px 18px;transition:border-color .15s,transform .15s,box-shadow .15s;background:#fff}
.pager a:hover{border-color:#d8deec;transform:translateY(-2px);box-shadow:var(--shadow)}
.pager .p-dir{font-size:11.5px;font-weight:700;letter-spacing:1.2px;text-transform:uppercase;color:var(--ink-soft)}
.pager .p-t{display:block;font-family:var(--display);font-weight:600;font-size:15.5px;margin-top:3px;color:var(--ink)}
.pager a.next{text-align:right}
.pager a.next .p-t{color:var(--ember-deep)}
@media(max-width:560px){.pager{grid-template-columns:1fr}}

/* footer */
footer.site{border-top:1px solid var(--line);padding:30px 0;color:var(--ink-soft);font-size:13.5px;margin-top:0}
footer.site .disclaimer{font-size:12.5px;color:#9097a6;margin:0 0 16px;padding-bottom:16px;border-bottom:1px solid var(--line);line-height:1.6}
footer.site .foot-row{display:flex;justify-content:space-between;flex-wrap:wrap;gap:12px}
footer.site a{color:var(--ink-soft);transition:color .15s}
footer.site a:hover{color:var(--ink)}

/* ---------- study hub (index) ---------- */
.hub-hero{background:radial-gradient(620px 420px at 84% -12%, rgba(232,82,31,.16), transparent 64%),linear-gradient(172deg,#0f1830 0%,var(--navy) 78%);color:#fff;padding:74px 0 66px;text-align:center}
.hub-hero .eyebrow{display:inline-block;font-size:12px;font-weight:600;letter-spacing:2px;text-transform:uppercase;color:#9aa6c0;padding-bottom:4px;border-bottom:1px solid rgba(255,255,255,.16)}
.hub-hero h1{font-family:var(--display);font-size:clamp(34px,5.6vw,54px);font-weight:700;letter-spacing:-1.4px;line-height:1.06;margin:20px auto 0;max-width:18ch}
.hub-hero h1 em{font-style:normal;color:var(--ember-light)}
.hub-hero p{font-size:clamp(15.5px,2vw,18px);color:#aeb7cd;max-width:56ch;margin:18px auto 0}
.hub-body{padding:56px 0 90px}
.hub-sec{margin-bottom:52px}
.hub-sec-head{display:flex;align-items:baseline;justify-content:space-between;gap:14px;flex-wrap:wrap;margin-bottom:20px}
.hub-sec-head h2{font-family:var(--display);font-size:clamp(21px,3vw,26px);font-weight:700;letter-spacing:-.5px}
.hub-sec-head .hs-k{font-size:12px;font-weight:700;letter-spacing:1.8px;text-transform:uppercase;color:var(--ember);display:block;margin-bottom:6px}
.hub-sec-head p{color:var(--ink-soft);font-size:15px;max-width:60ch}
.guide-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:18px}
@media(max-width:880px){.guide-grid{grid-template-columns:repeat(2,1fr)}}
@media(max-width:600px){.guide-grid{grid-template-columns:1fr}}
.gcard{display:flex;flex-direction:column;background:#fff;border:1px solid var(--line);border-radius:var(--radius);box-shadow:var(--shadow);padding:22px 22px 20px;transition:transform .18s,box-shadow .18s,border-color .18s;position:relative}
.gcard:hover{transform:translateY(-4px);box-shadow:0 18px 40px rgba(16,22,34,.12);border-color:#d8deec}
.gcard .g-num{font-family:var(--display);font-weight:700;font-size:12px;letter-spacing:1px;color:var(--ember);margin-bottom:10px}
.gcard h3{font-family:var(--display);font-size:18.5px;font-weight:700;letter-spacing:-.3px;margin-bottom:6px}
.gcard p{font-size:14px;color:var(--ink-soft);line-height:1.55;flex:1}
.gcard .g-foot{display:flex;align-items:center;justify-content:space-between;margin-top:16px;padding-top:14px;border-top:1px solid var(--line)}
.gcard .g-read{font-size:12.5px;font-weight:600;color:var(--ink-soft)}
.gcard .g-go{font-size:13.5px;font-weight:600;color:var(--ember)}
.gcard .g-game{display:inline-flex;align-items:center;gap:6px;font-size:12px;font-weight:600;color:var(--teal);background:#f0faf9;border:1px solid #c5e8e5;border-radius:999px;padding:3px 10px;margin-top:12px;align-self:flex-start}
.gcard.soon{opacity:.62;pointer-events:none}
.gcard.soon .g-go{color:var(--ink-soft)}

/* print: clean study handout */
@media print{
  nav.topnav,.side,.drill,.pager,footer.site .foot-row,.m-menu,.nav-burger{display:none!important}
  .study-shell{display:block;padding:0}
  article.study{max-width:none}
  .tbl-wrap,.algo,.quiz,.callout{box-shadow:none;break-inside:avoid}
  details.q{border-bottom:1px solid #ddd}
  details.q .q-a{display:block!important}
  body{font-size:12.5px}
}