/* CramSheet multi-page site — shared stylesheet */
:root{
  --paper:#fcfaf3; --bg:#f3f0e8; --ink:#1a1714; --muted:#6b6660; --line:#d9d2c2;
  --accent:#a0281d; --accent-soft:#f5e3e0;
  --blue:#1e3a5f; --blue-soft:#e0e8f1;
  --gold:#8a6d14; --gold-soft:#f3ebd4;
  --green:#2d5e3e; --green-soft:#dde9df;
  --code-bg:#23201c; --code-fg:#f0ebe2;
  --card:#ffffff; --nav:#1a1714;
  --radius:12px; --max:960px;
  --shadow:0 6px 24px rgba(26,23,20,.08);
}
*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{font-family:'Inter',-apple-system,'Segoe UI',sans-serif;background:var(--bg);color:var(--ink);line-height:1.7;font-size:16px}
a{color:var(--accent)}
code{font-family:'JetBrains Mono',monospace;background:rgba(0,0,0,.07);padding:1px 6px;border-radius:4px;font-size:.88em}
pre, .math{font-family:'JetBrains Mono',monospace;background:var(--code-bg);color:var(--code-fg);padding:14px 18px;border-radius:10px;font-size:13px;line-height:1.75;white-space:pre;overflow-x:auto;margin:12px 0;border:1px solid #000}
.math .v{color:#ffb86c}.math .op{color:#ff79c6}.math .c{color:#9a9288;font-style:italic}.math .r{color:#50fa7b;font-weight:700}.math .h{color:#f1fa8c}.math .b{color:#8be9fd}

/* NAV */
.site-nav{position:sticky;top:0;z-index:50;background:var(--nav);color:#fff;box-shadow:0 2px 12px rgba(0,0,0,.25)}
.nav-inner{max-width:1100px;margin:0 auto;padding:0 20px;display:flex;align-items:center;gap:18px;height:58px}
.brand{font-family:'Fraunces',serif;font-weight:900;font-size:20px;color:#fff;text-decoration:none;letter-spacing:-.02em;white-space:nowrap}
.brand em{color:#ff8a7a;font-style:italic}
.nav-links{display:flex;gap:4px;margin-left:auto;overflow-x:auto}
.nav-links a{color:#d8d2c6;text-decoration:none;font-size:13px;font-weight:600;padding:8px 11px;border-radius:7px;white-space:nowrap}
.nav-links a:hover{background:rgba(255,255,255,.12);color:#fff}
.nav-links a.active{background:var(--accent);color:#fff}
.menu-btn{display:none;background:none;border:1px solid rgba(255,255,255,.3);color:#fff;border-radius:7px;padding:6px 10px;font-size:16px;cursor:pointer;margin-left:auto}

/* HERO */
.hero{background:radial-gradient(circle at 88% 12%,rgba(160,40,29,.14),transparent 45%),radial-gradient(circle at 10% 90%,rgba(30,58,95,.12),transparent 45%),var(--paper);border-bottom:1px solid var(--line)}
.hero-inner{max-width:1100px;margin:0 auto;padding:52px 20px 40px}
.eyebrow{font-size:11px;text-transform:uppercase;letter-spacing:.25em;color:var(--accent);font-weight:800;margin-bottom:12px}
.hero h1{font-family:'Fraunces',serif;font-weight:900;font-size:clamp(38px,6vw,64px);line-height:1.02;letter-spacing:-.03em;margin-bottom:12px}
.hero h1 em{font-style:italic;color:var(--accent)}
.hero p.sub{font-family:'Fraunces',serif;font-style:italic;font-size:19px;color:var(--muted);max-width:640px;line-height:1.5}
.hero-meta{display:flex;gap:10px;flex-wrap:wrap;margin-top:18px}
.pill{font-size:11px;font-weight:700;letter-spacing:.08em;text-transform:uppercase;background:var(--ink);color:#fff;padding:5px 11px;border-radius:99px}
.pill.red{background:var(--accent)}.pill.blue{background:var(--blue)}.pill.green{background:var(--green)}
.btn{display:inline-block;background:var(--accent);color:#fff;text-decoration:none;font-weight:700;font-size:14px;padding:11px 20px;border-radius:9px;margin-top:20px;margin-right:10px}
.btn.secondary{background:var(--ink)}
.btn:hover{filter:brightness(1.1)}

/* LAYOUT */
.wrap{max-width:var(--max);margin:0 auto;padding:28px 20px 60px}
.breadcrumb{font-size:12.5px;color:var(--muted);margin-bottom:14px}
.breadcrumb a{color:var(--muted);text-decoration:none}.breadcrumb a:hover{color:var(--accent)}
.topic-head{margin-bottom:20px}
.sec-num{font-family:'Fraunces',serif;font-size:12px;color:var(--accent);font-weight:700;letter-spacing:.2em;text-transform:uppercase;margin-bottom:6px}
.topic-head h1{font-family:'Fraunces',serif;font-weight:900;font-size:clamp(30px,4.5vw,44px);line-height:1.05;letter-spacing:-.02em;margin-bottom:10px}
.lede{font-family:'Fraunces',serif;font-style:italic;font-size:17px;color:var(--muted);line-height:1.5;border-left:3px solid var(--accent);padding-left:14px;margin-bottom:8px}
h2{font-family:'Fraunces',serif;font-weight:800;font-size:23px;margin:28px 0 8px;letter-spacing:-.01em}
h3{font-family:'Fraunces',serif;font-weight:700;font-size:18px;margin:20px 0 6px}
h4{font-weight:700;font-size:12px;text-transform:uppercase;letter-spacing:.1em;color:var(--muted);margin:16px 0 6px}
p{margin-bottom:10px}
ul,ol{margin:0 0 12px 22px}li{margin-bottom:5px}

/* CARDS (home) */
.section-title{font-family:'Fraunces',serif;font-size:13px;text-transform:uppercase;letter-spacing:.18em;color:var(--muted);font-weight:800;margin:34px 0 14px;display:flex;align-items:center;gap:10px}
.section-title::after{content:'';flex:1;height:1px;background:var(--line)}
.cards{display:grid;grid-template-columns:repeat(auto-fill,minmax(270px,1fr));gap:14px}
.card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:18px;text-decoration:none;color:var(--ink);box-shadow:var(--shadow);display:flex;flex-direction:column;transition:transform .12s, box-shadow .12s}
.card:hover{transform:translateY(-3px);box-shadow:0 10px 30px rgba(26,23,20,.14)}
.card .n{font-family:'JetBrains Mono',monospace;font-size:11px;font-weight:700;color:var(--accent)}
.card h3{font-size:17px;margin:4px 0 6px}.card p{font-size:13.5px;color:var(--muted);flex:1}
.card .go{font-size:12.5px;font-weight:700;color:var(--accent);margin-top:10px}

/* BOXES */
.box{background:#fff;border:1px solid var(--line);border-radius:9px;padding:13px 16px;margin:12px 0;font-size:14.5px}
.box.accent{border-left:4px solid var(--accent);background:var(--accent-soft)}
.box.blue{border-left:4px solid var(--blue);background:var(--blue-soft)}
.box.gold{border-left:4px solid var(--gold);background:var(--gold-soft)}
.box.green{border-left:4px solid var(--green);background:var(--green-soft)}
.box .label{font-size:10.5px;text-transform:uppercase;letter-spacing:.14em;color:var(--muted);font-weight:800;margin-bottom:5px}
.theorem{background:#fff;border:1.5px solid var(--ink);border-radius:9px;padding:13px 16px;margin:12px 0}
.theorem .label{font-size:10.5px;text-transform:uppercase;letter-spacing:.14em;font-weight:800;color:var(--accent)}
.exam-tip{background:var(--gold-soft);border:1.5px dashed var(--gold);border-radius:9px;padding:12px 16px;margin:12px 0}

/* TABLES */
table.data{width:100%;border-collapse:collapse;margin:12px 0;font-size:13.5px;background:#fff;border-radius:9px;overflow:hidden;border:1px solid var(--line);display:block;overflow-x:auto}
table.data th{background:var(--ink);color:var(--paper);text-align:left;padding:8px 10px;font-size:11px;text-transform:uppercase;letter-spacing:.05em;white-space:nowrap}
table.data td{padding:8px 10px;border-top:1px solid var(--line);vertical-align:top}
table.data tr:nth-child(even) td{background:rgba(0,0,0,.025)}

/* STEPS */
.steps{counter-reset:step;margin:12px 0}
.step{position:relative;padding:8px 0 8px 40px;border-left:2px solid var(--line);margin-left:14px}
.step::before{counter-increment:step;content:counter(step);position:absolute;left:-14px;top:8px;width:26px;height:26px;background:var(--ink);color:#fff;border-radius:50%;display:flex;align-items:center;justify-content:center;font-size:12px;font-weight:800;font-family:'JetBrains Mono',monospace}
.step:last-child{border-left-color:transparent}

/* MATRIX + DIAGRAM */
.matrix{font-family:'JetBrains Mono',monospace;background:var(--code-bg);color:var(--code-fg);padding:12px 18px;border-radius:8px;font-size:14px;line-height:1.7;white-space:pre;display:inline-block;margin:8px 0;text-align:center}
.mx-label{font-size:11px;text-transform:uppercase;letter-spacing:.1em;color:var(--muted);font-weight:800;margin:10px 0 2px}
.mx-pair{display:flex;gap:12px;align-items:center;margin:10px 0;flex-wrap:wrap}
.mx-pair .arrow{color:var(--accent);font-weight:800;font-size:18px}
.diagram{background:#fff;border:1px solid var(--line);border-radius:10px;padding:16px;margin:14px 0;text-align:center}
.diagram svg{max-width:100%;height:auto}
.diagram .cap{font-size:12.5px;color:var(--muted);margin-top:8px;font-style:italic}
.tag{display:inline-block;font-size:10px;padding:2px 8px;border-radius:4px;background:var(--ink);color:#fff;font-weight:800;letter-spacing:.05em;text-transform:uppercase}
.tag.red{background:var(--accent)}.tag.blue{background:var(--blue)}.tag.green{background:var(--green)}

/* PREV NEXT */
.prevnext{display:flex;gap:12px;margin-top:36px;flex-wrap:wrap}
.prevnext a{flex:1;min-width:220px;background:#fff;border:1px solid var(--line);border-radius:10px;padding:14px 16px;text-decoration:none;color:var(--ink)}
.prevnext a:hover{border-color:var(--accent)}
.prevnext .dir{font-size:10.5px;text-transform:uppercase;letter-spacing:.14em;color:var(--muted);font-weight:800}
.prevnext .t{font-family:'Fraunces',serif;font-weight:700;font-size:16px}
.site-footer{background:var(--nav);color:#e8e2d6;margin-top:20px;padding:26px 20px;text-align:center;font-size:13.5px;border-top:3px solid var(--accent)}
.site-footer a{color:#ff8a7a;font-weight:700;text-decoration:underline}
.site-footer a:hover{color:#fff}

@media(max-width:760px){
  .nav-links{display:none;position:absolute;top:58px;left:0;right:0;background:var(--nav);flex-direction:column;padding:10px 16px 16px}
  .nav-links.open{display:flex}
  .menu-btn{display:block}
  body{font-size:15px}
  .hero-inner{padding:36px 18px 28px}
}