:root {
  --bg: #f6f7fb;
  --paper: #ffffff;
  --ink: #172033;
  --muted: #5f6b7a;
  --blue: #1e4f91;
  --blue-dark: #14284c;
  --gold: #d9a441;
  --gold-soft: #fff5dc;
  --green: #287a52;
  --red: #9e3d3d;
  --border: #d9dee8;
  --shadow: 0 14px 40px rgba(23, 32, 51, 0.08);
  --radius: 24px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--ink);
  line-height: 1.55;
}

header {
  background: radial-gradient(circle at top right, rgba(217,164,65,0.35), transparent 35%), linear-gradient(135deg, #101827, var(--blue-dark) 48%, var(--blue));
  color: white;
  padding: 4rem 1.5rem 3.5rem;
}

.container { max-width: 1180px; margin: 0 auto; }

.hero-grid {
  display: grid;
  grid-template-columns: 1.35fr 0.65fr;
  gap: 2rem;
  align-items: center;
}

.eyebrow {
  text-transform: uppercase;
  letter-spacing: 0.12em;
  font-size: 0.78rem;
  font-weight: 850;
  opacity: 0.9;
  margin-bottom: 0.75rem;
}

h1 {
  font-size: clamp(2.35rem, 5vw, 5rem);
  line-height: 0.98;
  margin: 0 0 1rem;
  max-width: 900px;
}

header p { max-width: 780px; font-size: 1.15rem; opacity: 0.95; margin: 0; }

.identity-card {
  background: rgba(255,255,255,0.12);
  border: 1px solid rgba(255,255,255,0.22);
  border-radius: 30px;
  padding: 1.25rem;
  box-shadow: 0 18px 45px rgba(0,0,0,0.18);
}

.logo-strip { display: grid; grid-template-columns: repeat(3, 1fr); gap: 0.75rem; margin-top: 1rem; }
.logo-tile {
  min-height: 92px;
  border-radius: 24px;
  display: grid;
  place-items: center;
  background: rgba(255,255,255,0.12);
  border: 1px solid rgba(255,255,255,0.20);
  color: var(--gold-soft);
  font-size: 2rem;
  font-weight: 950;
  text-align: center;
}

nav {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(255,255,255,0.96);
  border-bottom: 1px solid var(--border);
  backdrop-filter: blur(12px);
}

nav .container { display: flex; gap: 0.65rem; overflow-x: auto; padding: 0.85rem 1.5rem; }
nav a {
  color: var(--blue);
  text-decoration: none;
  font-weight: 850;
  padding: 0.5rem 0.8rem;
  border-radius: 999px;
  white-space: nowrap;
  font-size: 0.92rem;
}
nav a:hover { background: #edf3ff; }
nav a.active { background: var(--blue); color: white; }

main { padding: 2rem 1.5rem 4rem; }
section { max-width: 1180px; margin: 0 auto 3rem; scroll-margin-top: 86px; }

.section-shell {
  background: var(--paper);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: clamp(1.25rem, 4vw, 2.5rem);
  box-shadow: var(--shadow);
}

.page-hero {
  background: linear-gradient(135deg, var(--blue-dark), var(--blue));
  color: white;
  border-radius: 34px;
  padding: clamp(1.5rem, 4vw, 2.6rem);
  margin-bottom: 1.25rem;
  box-shadow: var(--shadow);
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 1rem;
  align-items: center;
  overflow: hidden;
  position: relative;
}

.page-hero::after {
  content: "";
  position: absolute;
  right: -80px;
  bottom: -110px;
  width: 250px;
  height: 250px;
  border-radius: 999px;
  background: rgba(217,164,65,0.25);
}

.page-hero h2 { color: white; margin: 0 0 0.5rem; }
.page-hero p { color: rgba(255,255,255,0.9); max-width: 780px; margin: 0; }

.page-logo {
  width: 116px;
  height: 116px;
  border-radius: 30px;
  background: linear-gradient(135deg, #fff7df, var(--gold));
  color: var(--blue-dark);
  display: grid;
  place-items: center;
  font-size: 2.8rem;
  font-weight: 950;
  border: 4px solid rgba(255,255,255,0.65);
  z-index: 1;
  text-align: center;
  line-height: 1;
}

h2 { font-size: clamp(1.8rem, 3vw, 2.8rem); margin: 0 0 0.75rem; line-height: 1.05; color: var(--blue-dark); }
h3 { margin: 0 0 0.55rem; color: var(--blue-dark); font-size: 1.25rem; }
.section-note { color: var(--muted); max-width: 760px; margin: 0 0 1.5rem; }

.grid { display: grid; grid-template-columns: repeat(12, 1fr); gap: 1rem; }
.card { background: var(--paper); border: 1px solid var(--border); border-radius: 24px; padding: 1.25rem; box-shadow: var(--shadow); }
.span-4 { grid-column: span 4; }
.span-6 { grid-column: span 6; }
.span-8 { grid-column: span 8; }
.span-12 { grid-column: span 12; }

.resource-card { border-top: 7px solid var(--gold); min-height: 100%; }
a.resource-card {
  display: block;
  color: inherit;
  text-decoration: none;
  transition: transform 160ms ease, box-shadow 160ms ease, border-color 160ms ease;
}
a.resource-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 18px 45px rgba(23, 32, 51, 0.15);
  border-color: rgba(217,164,65,0.75);
}
.card-link-note {
  display: inline-block;
  margin-top: 0.85rem;
  color: var(--blue);
  font-weight: 900;
}
.mini-logo { width: 68px; height: 68px; border-radius: 20px; display: grid; place-items: center; background: var(--blue-dark); color: var(--gold-soft); font-size: 1.8rem; font-weight: 950; margin-bottom: 1rem; }

.tag-row { display: flex; flex-wrap: wrap; gap: 0.45rem; margin: 0.75rem 0 1rem; }
.tag { display: inline-block; border-radius: 999px; padding: 0.25rem 0.6rem; font-size: 0.78rem; font-weight: 850; background: #edf3ff; color: var(--blue); }
.tag.gold { background: var(--gold-soft); color: #8a5d00; }
.tag.green { background: #e8f7ef; color: var(--green); }
.tag.red { background: #faeaea; color: var(--red); }

.term-list { display: grid; gap: 0.75rem; }
.term { border-left: 5px solid var(--blue); background: #fbfcff; padding: 0.9rem 1rem; border-radius: 16px; }
.term.gold-border { border-left-color: var(--gold); }
.term.green-border { border-left-color: var(--green); }
.term.red-border { border-left-color: var(--red); }
.term strong { display: block; font-size: 1.05rem; margin-bottom: 0.25rem; }
.term p, .card p { margin: 0.35rem 0; color: var(--muted); }

.formula-box, .equation-box { background: var(--blue-dark); color: white; border-radius: 20px; padding: 1rem; margin: 1rem 0; font-size: 1.05rem; overflow-x: auto; }
.formula-box code { font-family: "SFMono-Regular", Consolas, monospace; color: var(--gold-soft); font-weight: 850; }

.pace-table { width: 100%; border-collapse: collapse; margin-top: 1rem; overflow: hidden; border-radius: 16px; font-size: 0.95rem; }
.pace-table th, .pace-table td { border-bottom: 1px solid var(--border); text-align: left; padding: 0.8rem; vertical-align: top; }
.pace-table th { background: #edf3ff; color: var(--blue); }
.pace-table tr:last-child td { border-bottom: none; }

.calculator { display: grid; gap: 0.75rem; margin-top: 1rem; }
label { font-weight: 850; font-size: 0.9rem; }
input, select { width: 100%; border: 1px solid var(--border); border-radius: 14px; padding: 0.8rem; font: inherit; background: white; }
button { border: none; background: var(--blue); color: white; border-radius: 16px; padding: 0.9rem 1rem; font-weight: 900; cursor: pointer; }
button:hover { filter: brightness(1.08); }
.result { background: #edf3ff; border: 1px solid #c8d8f2; border-radius: 18px; padding: 1rem; color: var(--blue); font-weight: 850; }
.coach-note { border-radius: 18px; padding: 1rem; background: #fff9eb; border: 1px solid #f0dca5; color: #6d4c00; margin-top: 1rem; }

details { border: 1px solid var(--border); border-radius: 16px; padding: 1rem; background: white; margin: 1rem 0; }
summary { cursor: pointer; font-weight: 900; color: var(--blue); }

.print-button { position: fixed; right: 18px; bottom: 18px; z-index: 30; border-radius: 999px; box-shadow: 0 10px 25px rgba(30,79,145,0.32); }
footer { padding: 2rem 1.5rem; background: #101827; color: white; }
footer p { margin: 0; color: #cbd5e1; }

.breadcrumb { color: var(--muted); font-size: 0.9rem; margin-bottom: 1.5rem; }
.breadcrumb a { color: var(--blue); text-decoration: none; font-weight: 700; }
.breadcrumb a:hover { text-decoration: underline; }

.quicknav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  padding: 0.5rem 0;
}
.quicknav a {
  display: inline-block;
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 0.5rem 1rem;
  font-size: 0.88rem;
  font-weight: 850;
  color: var(--blue);
  text-decoration: none;
  background: var(--paper);
  transition: background 160ms ease, color 160ms ease;
}
.quicknav a:hover {
  background: var(--blue);
  color: white;
}

.svg-wrap {
  background: var(--paper);
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 1rem;
  overflow-x: auto;
}
.svg-wrap svg { max-width: 100%; height: auto; display: block; margin: auto; }

.derivation {
  background: #fbfcff;
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 1.25rem;
  margin: 1rem 0;
}
.derivation .step {
  border-left: 4px solid var(--gold);
  padding-left: 1rem;
  margin: 1rem 0;
}

@media (max-width: 880px) {
  .hero-grid, .page-hero { grid-template-columns: 1fr; }
  .span-4, .span-6, .span-8 { grid-column: span 12; }
  header { padding-top: 3rem; }
  .page-logo { width: 88px; height: 88px; font-size: 2.1rem; }
}

@media print {
  header, nav, .print-button { display: none; }
  body { background: white; }
  main { padding: 0; }
  section, .section-shell, .card { box-shadow: none; break-inside: avoid; }
}