/* OptionMath.com — 2026 rebuild
   Responsive, dependency-free. One stylesheet for the whole site. */

:root{
  --navy:#1a2a5e;
  --navy-deep:#111d42;
  --accent:#c2410c;
  --ink:#1c1f26;
  --muted:#5a6274;
  --rule:#e3e7ef;
  --bg:#ffffff;
  --bg-soft:#f6f8fc;
  --max:1080px;
  --radius:10px;
}

*,*::before,*::after{box-sizing:border-box}

html{-webkit-text-size-adjust:100%}

body{
  margin:0;
  background:var(--bg);
  color:var(--ink);
  font:400 17px/1.65 -apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif;
  -webkit-font-smoothing:antialiased;
}

.wrap{max-width:var(--max);margin:0 auto;padding:0 20px}

/* ---------- Header ---------- */
.site-header{
  border-bottom:1px solid var(--rule);
  background:var(--bg);
  position:sticky;top:0;z-index:50;
}
.header-inner{
  display:flex;align-items:center;justify-content:space-between;
  gap:20px;flex-wrap:wrap;padding:18px 20px;
  max-width:var(--max);margin:0 auto;
}
.brand{
  font-family:Georgia,"Times New Roman",serif;
  font-size:30px;line-height:1;color:var(--navy);
  text-decoration:none;font-weight:400;letter-spacing:-.01em;
  white-space:nowrap;
}
.brand:hover{color:var(--navy-deep)}

nav.main{display:flex;flex-wrap:wrap;gap:4px}
nav.main a{
  color:var(--muted);text-decoration:none;font-size:15px;
  padding:8px 11px;border-radius:6px;white-space:nowrap;
}
nav.main a:hover{color:var(--navy);background:var(--bg-soft)}
nav.main a[aria-current=page]{color:var(--navy);font-weight:600;background:var(--bg-soft)}

/* ---------- Hero ---------- */
.hero{
  background:linear-gradient(160deg,var(--navy) 0%,var(--navy-deep) 100%);
  color:#fff;padding:64px 0 60px;
}
.hero h1{
  margin:0 0 16px;font-size:clamp(30px,5vw,46px);line-height:1.15;
  font-weight:600;letter-spacing:-.02em;
}
.hero p{margin:0 0 28px;font-size:clamp(17px,2.2vw,20px);color:#c8d0e8;max-width:60ch}
.hero .wrap{max-width:var(--max)}

.btn{
  display:inline-block;background:#fff;color:var(--navy);
  padding:14px 26px;border-radius:var(--radius);text-decoration:none;
  font-weight:600;font-size:16px;border:2px solid #fff;transition:.15s;
}
.btn:hover{background:transparent;color:#fff}
.btn-ghost{background:transparent;color:#fff;border-color:rgba(255,255,255,.45);margin-left:10px}
.btn-ghost:hover{background:#fff;color:var(--navy);border-color:#fff}

/* ---------- Page head ---------- */
.page-head{border-bottom:1px solid var(--rule);padding:40px 0 30px;background:var(--bg-soft)}
.page-head h1{margin:0;font-size:clamp(26px,4vw,38px);line-height:1.2;color:var(--navy);font-weight:600;letter-spacing:-.02em}
.page-head .kicker{margin:0 0 8px;font-size:13px;letter-spacing:.09em;text-transform:uppercase;color:var(--accent);font-weight:600}
.page-head p.lede{margin:14px 0 0;color:var(--muted);font-size:19px;max-width:62ch}

/* ---------- Content ---------- */
main{padding:44px 0 72px}
main h2{font-size:26px;margin:38px 0 12px;color:var(--navy);font-weight:600;letter-spacing:-.01em}
main h3{font-size:20px;margin:28px 0 8px;color:var(--navy);font-weight:600}
main p{margin:0 0 18px;max-width:70ch}
main ul,main ol{max-width:70ch;padding-left:22px}
main li{margin-bottom:8px}
main a{color:var(--accent);text-decoration:underline;text-underline-offset:2px}
main a:hover{color:var(--navy)}
.prose>*:first-child{margin-top:0}

.callout{
  background:var(--bg-soft);border-left:3px solid var(--navy);
  padding:18px 22px;border-radius:0 var(--radius) var(--radius) 0;margin:26px 0;
}
.callout p{margin:0}

.warn{
  background:#fff7ed;border-left:3px solid var(--accent);
  padding:18px 22px;border-radius:0 var(--radius) var(--radius) 0;margin:26px 0;
}
.warn p{margin:0}

/* ---------- Strategy grid ---------- */
.grid{
  display:grid;gap:18px;margin:32px 0 0;
  grid-template-columns:repeat(auto-fill,minmax(220px,1fr));
}
.card{
  border:1px solid var(--rule);border-radius:var(--radius);
  padding:18px;text-decoration:none;color:inherit;display:block;
  transition:.15s;background:var(--bg);
}
.card:hover{border-color:var(--navy);box-shadow:0 4px 16px rgba(26,42,94,.09);transform:translateY(-2px)}
.card img{width:100%;height:auto;display:block;margin-bottom:12px}
.card .label{font-weight:600;color:var(--navy);font-size:16px;line-height:1.3}

/* ---------- Strategy page figure ---------- */
.figure{
  border:1px solid var(--rule);border-radius:var(--radius);
  padding:22px;margin:0 0 30px;background:var(--bg-soft);max-width:340px;
}
.figure img{width:100%;height:auto;display:block}
.figure figcaption{margin-top:10px;font-size:13px;color:var(--muted);text-align:center}

/* ---------- Resource links ---------- */
.res{
  display:flex;align-items:center;gap:12px;
  border:1px solid var(--rule);border-radius:var(--radius);
  padding:15px 18px;text-decoration:none;color:var(--navy);
  font-weight:600;margin-bottom:10px;transition:.15s;max-width:70ch;
}
.res:hover{border-color:var(--navy);background:var(--bg-soft)}
.res .ico{flex:none;width:22px;height:22px;color:var(--accent)}
.res .meta{font-weight:400;color:var(--muted);font-size:14px;margin-left:auto;white-space:nowrap}

/* ---------- Books ---------- */
.book{display:grid;grid-template-columns:150px 1fr;gap:28px;margin:0 0 48px;align-items:start}
.book img{width:100%;height:auto;border-radius:6px;box-shadow:0 3px 14px rgba(0,0,0,.16)}
.book h2{margin-top:0}
.book .imprint{color:var(--muted);font-size:15px;margin:-6px 0 16px}

/* ---------- Phenomena ---------- */
.phen{border-top:1px solid var(--rule);padding:24px 0}
.phen:last-of-type{border-bottom:1px solid var(--rule)}
.phen h3{margin:0 0 6px}
.phen p{margin:0;color:var(--muted)}

/* ---------- Footer ---------- */
.site-footer{
  border-top:1px solid var(--rule);background:var(--bg-soft);
  padding:36px 0;color:var(--muted);font-size:14px;
}
.footer-inner{display:flex;justify-content:space-between;gap:24px;flex-wrap:wrap;align-items:center}
.site-footer a{color:var(--muted);text-decoration:none}
.site-footer a:hover{color:var(--navy);text-decoration:underline}
.footer-nav{display:flex;gap:18px;flex-wrap:wrap}

/* ---------- Responsive ---------- */
@media (max-width:720px){
  body{font-size:16px}
  .header-inner{padding:14px 20px;gap:12px}
  .brand{font-size:25px}
  nav.main{gap:2px;width:100%}
  nav.main a{padding:7px 9px;font-size:14px}
  .hero{padding:44px 0 40px}
  .btn-ghost{margin-left:0;margin-top:10px}
  .book{grid-template-columns:110px 1fr;gap:18px}
  .grid{grid-template-columns:repeat(auto-fill,minmax(150px,1fr));gap:12px}
  .card{padding:13px}
  main{padding:32px 0 52px}
}

@media (prefers-reduced-motion:reduce){
  *{transition:none!important;transform:none!important}
}