:root{
  --navy:#0a1733;
  --navy-2:#13234d;
  --navy-3:#1d3066;
  --amber:#f5a524;
  --amber-2:#d98b0c;
  --amber-soft:#fef3d6;
  --cream:#fbf8f1;
  --paper:#ffffff;
  --ink:#0e1726;
  --ink-2:#23304a;
  --muted:#5b657a;
  --muted-2:#8590a4;
  --line:#e7e2d4;
  --line-2:#f0ebde;
  --max:1180px;
  --shadow-card:0 1px 0 rgba(10,23,51,.04),0 18px 36px -28px rgba(10,23,51,.18);
  --shadow-hero:0 28px 70px -22px rgba(0,0,0,.55);
}
*{box-sizing:border-box}
html,body{margin:0;padding:0;background:var(--cream);color:var(--ink);font-family:'Inter','Helvetica Neue',Arial,sans-serif;line-height:1.65;font-size:17px;-webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility}
img{max-width:100%;display:block}
a{color:var(--navy);text-decoration:none;border-bottom:1px solid rgba(10,23,51,.2);transition:.18s ease}
a:hover{color:var(--amber-2);border-bottom-color:var(--amber)}
.container{max-width:var(--max);margin:0 auto;padding:0 24px}

/* ---------- Header ---------- */
header.site{background:var(--navy);color:#fff;border-bottom:3px solid var(--amber);position:sticky;top:0;z-index:50}
header.site .container{display:flex;align-items:center;gap:24px;padding-top:14px;padding-bottom:14px}
header.site a{color:#fff;border:none}
header.site .brand{font-weight:800;letter-spacing:-.01em;font-size:21px;display:flex;align-items:center;gap:11px}
header.site .brand .mark{width:34px;height:34px;background:var(--amber);border-radius:8px;display:grid;place-items:center;color:var(--navy);font-weight:900;font-size:18px;box-shadow:0 6px 14px -6px rgba(245,165,36,.65)}
header.site .brand small{display:block;font-size:11px;font-weight:500;opacity:.75;margin-top:1px;letter-spacing:.04em;text-transform:uppercase}
header.site .brand .stack{line-height:1.05}
nav.primary{margin-left:auto;display:flex;gap:24px;flex-wrap:wrap;font-size:14px;font-weight:600;letter-spacing:.01em}
nav.primary a{opacity:.82;border-bottom:2px solid transparent;padding:4px 0}
nav.primary a:hover{opacity:1;color:var(--amber);border-bottom-color:var(--amber)}

/* ---------- Hero ---------- */
.hero{background:radial-gradient(1100px 460px at 80% -10%,rgba(245,165,36,.18),transparent 60%),linear-gradient(170deg,var(--navy) 0%,var(--navy-2) 60%,var(--navy-3) 100%);color:#fff;padding:72px 0 84px;position:relative;overflow:hidden}
.hero:after{content:"";position:absolute;left:0;right:0;bottom:-1px;height:60px;background:linear-gradient(180deg,transparent,var(--cream))}
.hero .container{display:grid;grid-template-columns:1.15fr .9fr;gap:48px;align-items:center;position:relative;z-index:2}
.eyebrow{display:inline-flex;align-items:center;gap:8px;background:rgba(245,165,36,.15);color:var(--amber);font-size:12px;font-weight:700;letter-spacing:.12em;text-transform:uppercase;padding:7px 14px;border-radius:999px;border:1px solid rgba(245,165,36,.35)}
.eyebrow .dot{width:6px;height:6px;border-radius:50%;background:var(--amber)}
.hero h1{font-weight:800;font-size:54px;line-height:1.05;letter-spacing:-.025em;margin:18px 0 18px;color:#fff;max-width:14ch}
.hero h1 em{color:var(--amber);font-style:normal;border-bottom:3px solid rgba(245,165,36,.5);padding-bottom:2px}
.hero p.lead{font-size:19px;color:#dde4f3;opacity:1;margin:0 0 28px;max-width:50ch;font-weight:400}
.hero .cta-row{display:flex;flex-wrap:wrap;gap:12px}
.cta{display:inline-flex;align-items:center;gap:8px;background:var(--amber);color:var(--navy);padding:14px 24px;border-radius:10px;font-weight:700;font-size:15px;border:none;letter-spacing:-.005em;box-shadow:0 10px 24px -10px rgba(245,165,36,.55)}
.cta:hover{background:var(--amber-2);color:#fff}
.cta.ghost{background:transparent;border:1.5px solid rgba(255,255,255,.35);color:#fff;box-shadow:none}
.cta.ghost:hover{background:rgba(255,255,255,.08);border-color:var(--amber);color:var(--amber)}
.hero .visual{position:relative}
.hero .visual img{border-radius:16px;box-shadow:var(--shadow-hero);border:1px solid rgba(255,255,255,.05)}
.hero-stats{display:grid;grid-template-columns:repeat(3,1fr);gap:14px;margin-top:32px;max-width:540px}
.hero-stats .fact{background:rgba(255,255,255,.04);border:1px solid rgba(255,255,255,.08);padding:14px 16px;border-radius:12px;backdrop-filter:blur(6px)}
.hero-stats .n{font-weight:800;font-size:26px;color:var(--amber);display:block;line-height:1;letter-spacing:-.02em}
.hero-stats .l{font-size:11.5px;text-transform:uppercase;letter-spacing:.1em;color:rgba(255,255,255,.7);margin-top:6px;display:block;font-weight:600}

/* ---------- Page chrome ---------- */
main{padding:54px 0 70px}
section{margin-bottom:48px}
h1,h2,h3,h4,h5{font-weight:800;color:var(--navy);line-height:1.18;letter-spacing:-.02em}
h1{font-size:42px;margin:0 0 14px;letter-spacing:-.03em}
h2{font-size:28px;margin:0 0 16px;padding-bottom:10px;border-bottom:1px solid var(--line)}
h2 .count{font-size:13px;font-weight:600;color:var(--muted);background:var(--paper);padding:3px 10px;border-radius:999px;border:1px solid var(--line);vertical-align:middle;margin-left:8px;letter-spacing:.04em}
h3{font-size:20px;margin:22px 0 10px;letter-spacing:-.015em}
h4{font-size:14px;text-transform:uppercase;letter-spacing:.1em;color:var(--muted)}
.lead{font-size:18.5px;color:var(--ink-2);max-width:64ch;line-height:1.55}

.crumbs{font-size:12.5px;color:var(--muted);text-transform:uppercase;letter-spacing:.09em;margin-bottom:14px;font-weight:600}
.crumbs a{color:var(--muted);border:none}
.crumbs a:hover{color:var(--amber-2)}
.crumbs .sep{margin:0 8px;color:var(--muted-2)}

/* ---------- Cards & grids ---------- */
.grid{display:grid;gap:18px}
.grid.cols-2{grid-template-columns:repeat(2,minmax(0,1fr))}
.grid.cols-3{grid-template-columns:repeat(3,minmax(0,1fr))}
.grid.cols-4{grid-template-columns:repeat(4,minmax(0,1fr))}
.card{background:var(--paper);border:1px solid var(--line);border-radius:14px;padding:22px 22px 20px;transition:.2s ease;display:block;color:inherit;border-bottom:1px solid var(--line);position:relative}
a.card:hover{transform:translateY(-2px);box-shadow:var(--shadow-card);border-color:var(--amber);color:inherit}
.card .meta{font-size:11.5px;text-transform:uppercase;letter-spacing:.1em;color:var(--muted);font-weight:700}
.card h3{margin:8px 0 6px;color:var(--navy)}
.card p{margin:6px 0 0;color:var(--ink-2);font-size:14.5px;line-height:1.55}
.card .more{margin-top:14px;font-size:13px;font-weight:700;color:var(--amber-2);letter-spacing:-.005em}
a.card .more:after{content:" →";transition:margin .2s}
a.card:hover .more:after{margin-left:4px}

.tag{display:inline-block;background:var(--cream);color:var(--muted);font-size:11px;text-transform:uppercase;letter-spacing:.09em;padding:3px 10px;border-radius:999px;margin-right:6px;font-weight:700;border:1px solid var(--line)}
.tag.sat{background:#e6edff;color:#1d3a9b;border-color:#d2dcfa}
.tag.act{background:#fff0e0;color:#8c4012;border-color:#facfa3}
.tag.amber{background:var(--amber-soft);color:var(--amber-2);border-color:#f5dfa3}
.diff-easy{background:#e7f6ec;color:#1f6f3b;border-color:#c8ebd2}
.diff-medium{background:#fff4d4;color:#7a5a00;border-color:#f5e2a4}
.diff-hard{background:#ffe1e1;color:#9b1d1d;border-color:#f5c2c2}

/* ---------- Layout w/ sidebar ---------- */
.layout{display:grid;grid-template-columns:minmax(0,1fr) 300px;gap:48px;align-items:flex-start}
.sidebar{position:sticky;top:78px;font-size:14.5px}
.sidebar .panel{background:var(--paper);border:1px solid var(--line);border-radius:12px;padding:18px 18px 14px;margin-bottom:18px}
.sidebar h4{font-size:11.5px;text-transform:uppercase;letter-spacing:.1em;color:var(--muted);margin:0 0 10px;font-weight:700}
.sidebar ul{list-style:none;padding:0;margin:0}
.sidebar li{margin:6px 0}
.sidebar a{border:none;color:var(--ink-2)}
.sidebar a:hover{color:var(--amber-2)}
.related-block{background:linear-gradient(180deg,#fffaef 0%,#ffffff 100%);border:1px solid var(--line);border-radius:12px;padding:18px;margin-bottom:18px}
.related-block h4{color:var(--navy);font-size:12px;letter-spacing:.1em;font-weight:700;text-transform:uppercase;margin:0 0 4px}
.related-block .sub{font-size:12px;color:var(--muted);margin:0 0 12px}
.related-block ul{list-style:none;padding:0;margin:0}
.related-block li{padding:9px 0;border-top:1px solid var(--line-2);font-size:14px;line-height:1.4}
.related-block li:first-child{border-top:none;padding-top:2px}
.related-block li a{color:var(--navy);font-weight:600;border:none}
.related-block li a:hover{color:var(--amber-2)}
.related-block li .src{display:block;font-size:11px;color:var(--muted);font-weight:500;margin-top:2px;letter-spacing:.02em}

/* ---------- Notes / content blocks ---------- */
.notes{background:var(--paper);border:1px solid var(--line);border-radius:14px;padding:28px 32px;margin-bottom:24px;font-size:16.5px;line-height:1.72;color:var(--ink-2)}
.notes p{margin:0 0 14px}
.notes p:last-child{margin-bottom:0}
.notes h3{margin:24px 0 8px;color:var(--navy);font-size:18.5px}
.notes ul{margin:6px 0 14px;padding-left:22px}
.notes li{margin:6px 0}
.notes strong{color:var(--navy)}

.callout{background:#fffaef;border-left:4px solid var(--amber);border-radius:6px;padding:16px 22px;margin:22px 0;color:var(--ink-2)}
.callout strong{color:var(--navy)}
.cheat-formulas{list-style:none;padding:0;margin:14px 0;display:grid;grid-template-columns:1fr 1fr;gap:8px}
.cheat-formulas li{background:#fbfaf3;border:1px solid var(--line);padding:10px 14px;border-radius:8px}
.cheat-formulas .formula{font-family:'Source Serif Pro','Cambria',serif;color:var(--navy);font-weight:600;font-size:15px}
@media (max-width:560px){.cheat-formulas{grid-template-columns:1fr}}

/* ---------- Questions ---------- */
.question{background:var(--paper);border:1px solid var(--line);border-radius:14px;padding:22px 24px;margin-bottom:18px}
.question .head{display:flex;justify-content:space-between;align-items:center;font-size:12.5px;color:var(--muted);text-transform:uppercase;letter-spacing:.09em;margin-bottom:8px;font-weight:700}
.question .prompt{font-size:17px;line-height:1.6;margin:6px 0 14px;color:var(--ink)}
.choices{list-style:none;padding:0;margin:0 0 14px;display:grid;gap:8px}
.choices li{background:#fbfaf3;border:1px solid var(--line);padding:10px 14px;border-radius:9px;font-size:15px;color:var(--ink-2)}
.choices li b{display:inline-block;width:22px;color:var(--amber-2);font-weight:700}
details.solution{border-top:1px dashed var(--line);padding-top:12px;margin-top:8px}
details.solution summary{cursor:pointer;font-weight:700;color:var(--navy);margin-bottom:6px;font-size:14px;list-style:none;display:inline-flex;align-items:center;gap:6px}
details.solution summary:before{content:"▸";color:var(--amber);transition:transform .15s;display:inline-block}
details.solution[open] summary:before{transform:rotate(90deg)}
.solution .step{margin:8px 0;padding-left:16px;border-left:2px solid var(--amber);color:var(--ink-2);font-size:15px}
.solution .answer{margin-top:14px;font-weight:700;color:var(--navy);background:var(--amber-soft);border:1px solid #f5dfa3;padding:10px 14px;border-radius:8px;display:inline-block;font-size:14.5px}

/* ---------- AdSense placeholder ---------- */
.adsense{background:repeating-linear-gradient(45deg,#f7f3ec,#f7f3ec 8px,#efe9de 8px,#efe9de 16px);border:1px dashed #c7bfa9;color:#8a7c5a;font-size:12px;text-align:center;padding:14px;border-radius:8px;margin:18px 0}

/* ---------- Topic / index lists ---------- */
.topic-list{list-style:none;padding:0;margin:0;display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:6px 28px}
.topic-list li{padding:9px 0;border-bottom:1px dotted var(--line);font-size:15px;display:flex;justify-content:space-between;align-items:baseline;gap:12px}
.topic-list a{border:none;color:var(--navy);font-weight:500}
.topic-list a:hover{color:var(--amber-2)}
.topic-list .qcount{font-size:11px;color:var(--muted-2);font-weight:600;letter-spacing:.05em}

/* ---------- Footer ---------- */
footer.site{background:var(--navy);color:#cfd6e6;padding:48px 0 24px;border-top:3px solid var(--amber);font-size:14.5px;margin-top:48px}
footer.site a{color:#fff;border:none;opacity:.78}
footer.site a:hover{color:var(--amber);opacity:1}
footer.site .cols{display:grid;grid-template-columns:1.6fr 1fr 1fr 1fr;gap:32px;margin-bottom:28px}
footer.site h5{margin:0 0 12px;color:#fff;font-size:12px;text-transform:uppercase;letter-spacing:.1em;font-weight:700}
footer.site ul{list-style:none;padding:0;margin:0}
footer.site li{margin:5px 0}
footer.site .legal{border-top:1px solid rgba(255,255,255,.08);padding-top:18px;display:flex;justify-content:space-between;color:#9aa3b8;font-size:12px;flex-wrap:wrap;gap:14px}

/* ---------- Section header strip ---------- */
.section-head{display:flex;justify-content:space-between;align-items:flex-end;margin-bottom:18px;gap:16px;border-bottom:1px solid var(--line);padding-bottom:10px}
.section-head h2{border:none;padding:0;margin:0}
.section-head a{font-size:13px;font-weight:700;color:var(--amber-2);border:none}

/* ---------- Domain bars (homepage) ---------- */
.domain-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:18px}
.domain-card{background:var(--paper);border:1px solid var(--line);border-radius:14px;padding:24px;border-top:4px solid var(--amber);color:inherit}
.domain-card h3{margin:0 0 4px}
.domain-card .pct{font-size:12px;color:var(--muted);font-weight:700;letter-spacing:.06em;text-transform:uppercase}
.domain-card .bar{height:8px;background:var(--line-2);border-radius:99px;margin:14px 0 10px;overflow:hidden}
.domain-card .bar span{display:block;height:100%;background:linear-gradient(90deg,var(--amber),var(--amber-2));border-radius:99px}
.domain-card .skills{display:flex;flex-wrap:wrap;gap:6px;margin-top:10px}
.domain-card .skills a{font-size:12px;background:var(--cream);border:1px solid var(--line);color:var(--ink-2);padding:4px 9px;border-radius:6px;font-weight:600;border-bottom:1px solid var(--line)}
.domain-card .skills a:hover{background:var(--amber-soft);color:var(--amber-2);border-color:var(--amber)}

/* ---------- Formula sheet ---------- */
.formula-table{width:100%;border-collapse:collapse;background:var(--paper);border:1px solid var(--line);border-radius:12px;overflow:hidden;margin:18px 0;font-size:15px}
.formula-table th{text-align:left;background:var(--cream);padding:12px 16px;color:var(--navy);font-weight:700;font-size:13px;text-transform:uppercase;letter-spacing:.06em;border-bottom:1px solid var(--line)}
.formula-table td{padding:12px 16px;border-bottom:1px solid var(--line-2);vertical-align:top}
.formula-table tr:last-child td{border-bottom:none}
.formula-table .formula{font-family:'Source Serif Pro','Cambria',serif;font-size:16px;color:var(--navy);font-weight:600;background:#fbfaf3;padding:6px 10px;border-radius:6px;display:inline-block}
.formula-table .when{color:var(--muted);font-size:13.5px}

/* ---------- Score band card ---------- */
.band-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:18px;margin:20px 0 30px}
.band-card{background:var(--paper);border:1px solid var(--line);border-radius:14px;padding:22px;border-top:4px solid var(--amber);color:inherit}
.band-card .score{font-size:32px;font-weight:800;color:var(--navy);letter-spacing:-.03em;margin:0}
.band-card .pct{font-size:12.5px;color:var(--muted);font-weight:700;letter-spacing:.06em;text-transform:uppercase}
.band-card p{font-size:14.5px;color:var(--ink-2);margin:10px 0 0}

/* ---------- Pill / marker ---------- */
.exam-pill{display:inline-block;font-size:11px;text-transform:uppercase;letter-spacing:.1em;padding:5px 11px;border-radius:999px;background:var(--amber);color:var(--navy);font-weight:700}
.exam-pill.act{background:#fff0e0;color:#8c4012;border:1px solid #facfa3}

/* ---------- Mobile ---------- */
@media (max-width:920px){
  .hero{padding:48px 0 60px}
  .hero .container{grid-template-columns:1fr;gap:30px}
  .hero h1{font-size:38px}
  .hero p.lead{font-size:17px}
  .layout{grid-template-columns:1fr;gap:32px}
  .sidebar{position:static}
  .grid.cols-3,.grid.cols-4,.domain-grid,.band-grid{grid-template-columns:1fr 1fr}
  .topic-list{grid-template-columns:1fr}
  footer.site .cols{grid-template-columns:1fr 1fr}
  nav.primary{font-size:13px;gap:14px}
  header.site .container{flex-wrap:wrap}
  h1{font-size:32px}
  h2{font-size:24px}
}
@media (max-width:560px){
  .hero h1{font-size:32px}
  .grid.cols-2,.grid.cols-3,.grid.cols-4,.domain-grid,.band-grid{grid-template-columns:1fr}
  .hero-stats{grid-template-columns:1fr 1fr}
  footer.site .cols{grid-template-columns:1fr}
  footer.site .legal{flex-direction:column}
}