:root {
  color-scheme: light dark;
  --ink: #172033;
  --muted: #61708a;
  --paper: #f5f7fb;
  --surface: rgba(255, 255, 255, 0.88);
  --line: rgba(76, 91, 120, 0.18);
  --violet: #5c45c7;
  --violet-soft: #ece9ff;
  --teal: #087f78;
  --teal-soft: #dff7f3;
  --shadow: 0 18px 60px rgba(29, 38, 61, 0.12);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  color: var(--ink);
  background:
    radial-gradient(circle at 82% 8%, rgba(92, 69, 199, 0.13), transparent 28rem),
    radial-gradient(circle at 8% 55%, rgba(8, 127, 120, 0.11), transparent 30rem),
    var(--paper);
  font: 16px/1.6 Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont,
    "Segoe UI", sans-serif;
  min-height: 100vh;
}

a { color: inherit; }

.shell {
  width: min(1120px, calc(100% - 2.5rem));
  margin-inline: auto;
}

.hero,
.family-hero {
  position: relative;
  overflow: hidden;
  color: #f9fbff;
  background:
    linear-gradient(120deg, rgba(12, 20, 39, 0.97), rgba(32, 35, 87, 0.94)),
    repeating-linear-gradient(90deg, transparent 0 59px, rgba(255,255,255,.07) 60px),
    repeating-linear-gradient(0deg, transparent 0 59px, rgba(255,255,255,.07) 60px);
}

.hero::after,
.family-hero::after {
  content: "∀ n · Prime(p) · n < p < n + n · QRes(p,q)";
  position: absolute;
  right: -2rem;
  bottom: -1.5rem;
  color: rgba(255, 255, 255, 0.055);
  font: 700 clamp(2.5rem, 7vw, 7rem)/1 ui-monospace, monospace;
  white-space: nowrap;
  transform: rotate(-4deg);
  pointer-events: none;
}

.hero { padding: 3.5rem 0 5.5rem; }
.family-hero { padding: 2.1rem 0 4.8rem; }

.site-mark {
  display: inline-block;
  margin-bottom: 5rem;
  color: #d9e0f5;
  font-size: 0.84rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-decoration: none;
  text-transform: uppercase;
}

.eyebrow,
.card-kicker {
  margin: 0 0 0.65rem;
  color: #94e5dc;
  font-size: 0.75rem;
  font-weight: 800;
  letter-spacing: 0.13em;
  text-transform: uppercase;
}

h1,
h2,
p { margin-top: 0; }

h1 {
  max-width: 940px;
  margin-bottom: 1.25rem;
  font-family: Georgia, "Times New Roman", serif;
  font-size: clamp(2.75rem, 7vw, 6.4rem);
  font-weight: 600;
  letter-spacing: -0.045em;
  line-height: 0.98;
}

.lede {
  max-width: 760px;
  margin-bottom: 2rem;
  color: #c7d1e6;
  font-size: clamp(1.05rem, 2vw, 1.28rem);
}

.trust-row,
.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.trust-row span {
  padding: 0.45rem 0.8rem;
  border: 1px solid rgba(255, 255, 255, 0.17);
  border-radius: 999px;
  color: #d8e0f1;
  background: rgba(255, 255, 255, 0.055);
  font-size: 0.78rem;
  font-weight: 650;
}

.family-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1.25rem;
  margin-top: -2.35rem;
  position: relative;
  z-index: 2;
}

.family-card,
.view-card,
.method-note,
.release-note {
  border: 1px solid var(--line);
  border-radius: 22px;
  background: var(--surface);
  box-shadow: var(--shadow);
  backdrop-filter: blur(16px);
}

.family-card { padding: clamp(1.5rem, 4vw, 2.5rem); }
.family-card .card-kicker { color: var(--violet); }
.bertrand-card .card-kicker { color: var(--teal); }

.family-card h2,
.view-card h2,
.method-note h2 {
  margin-bottom: 0.75rem;
  font: 600 clamp(1.5rem, 3vw, 2.2rem)/1.12 Georgia, "Times New Roman", serif;
  letter-spacing: -0.025em;
}

.family-card > p:not(.card-kicker),
.view-card > p:not(.card-kicker),
.method-note > p:last-child {
  color: var(--muted);
}

.stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.7rem;
  margin: 1.7rem 0;
}

.stats div {
  padding: 0.7rem;
  border-radius: 13px;
  background: rgba(92, 69, 199, 0.07);
}

.bertrand-card .stats div { background: rgba(8, 127, 120, 0.07); }

.stats dt { font-size: 1.15rem; font-weight: 800; }
.stats dd { margin: 0; color: var(--muted); font-size: 0.72rem; }

.primary-action,
.secondary-action {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 0.7rem 1rem;
  border-radius: 11px;
  font-weight: 750;
  text-decoration: none;
}

.primary-action { color: #fff; background: var(--violet); }
.bertrand-card .primary-action,
.bertrand-page .primary-action { background: var(--teal); }
.secondary-action { color: #f6f8ff; border: 1px solid rgba(255,255,255,.28); }

.primary-action:hover,
.secondary-action:hover,
.view-card a:hover { transform: translateY(-1px); }

.method-note {
  margin: 4rem 0;
  padding: clamp(1.5rem, 5vw, 3rem);
}

.method-note .eyebrow { color: var(--teal); }
footer { padding: 0 0 3rem; color: var(--muted); font-size: 0.86rem; }

.frontier-intro {
  margin: 4.1rem 0 1rem;
  max-width: 900px;
}

.frontier-intro .eyebrow { color: var(--teal); }
.frontier-intro h2 {
  margin-bottom: 0.7rem;
  font: 600 clamp(1.6rem, 3vw, 2.45rem)/1.12 Georgia, "Times New Roman", serif;
  letter-spacing: -0.03em;
}
.frontier-intro > p:not(.eyebrow):not(.candidate-disclaimer) { color: var(--muted); }

.candidate-disclaimer,
.candidate-badge {
  display: inline-block;
  padding: 0.45rem 0.72rem;
  border: 1px solid rgba(188, 126, 29, 0.3);
  border-radius: 9px;
  background: rgba(224, 176, 72, 0.12);
  color: #805507;
  font-size: 0.74rem;
  font-weight: 760;
}

.frontier-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
  margin-top: 1.2rem;
}

.candidate-card { display: flex; flex-direction: column; padding: 1.35rem; }
.candidate-card h2 { font-size: 1.6rem; }
.candidate-card .card-kicker { font-size: 0.65rem; }
.candidate-card .candidate-badge { align-self: flex-start; margin-top: auto; }
.candidate-card .primary-action { align-self: flex-start; font-size: 0.82rem; }
.supplementary-card .card-kicker,
.supplementary-card .primary-action { color: #7152ba; }
.supplementary-card .primary-action { color: #fff; background: #7152ba; }
.kummer-card .card-kicker { color: #086f8d; }
.kummer-card .primary-action { background: #086f8d; }
.two-squares-card .card-kicker { color: #15735b; }
.two-squares-card .primary-action { background: #15735b; }
.four-squares-card .card-kicker { color: #9b5832; }
.four-squares-card .primary-action { background: #9b5832; }
.lucas-card .card-kicker { color: #465db1; }
.lucas-card .primary-action { background: #465db1; }
.pythagorean-card .card-kicker { color: #9a4268; }
.pythagorean-card .primary-action { background: #9a4268; }

.crumbs {
  display: flex;
  gap: 0.6rem;
  margin-bottom: 5rem;
  color: #aebad2;
  font-size: 0.82rem;
}

.crumbs a { color: #fff; }
.family-hero h1 { margin-bottom: 0.65rem; }

.formula {
  margin-bottom: 1.2rem;
  color: #94e5dc;
  font: 600 clamp(1.15rem, 3vw, 1.7rem)/1.2 ui-monospace, monospace;
}

.family-main { padding: 3.5rem 0 4rem; }

.view-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1rem;
}

.view-card { padding: 1.5rem; box-shadow: 0 10px 35px rgba(29,38,61,.08); }
.view-card.featured { border-color: rgba(92, 69, 199, 0.35); }
.bertrand-page .view-card.featured { border-color: rgba(8, 127, 120, 0.35); }
.view-card .card-kicker { color: var(--violet); }
.bertrand-page .view-card .card-kicker { color: var(--teal); }
.view-card h2 { font-size: 1.45rem; }
.view-card a { color: var(--violet); font-weight: 800; text-decoration: none; }
.bertrand-page .view-card a { color: var(--teal); }

.release-note {
  margin-top: 1rem;
  padding: 1rem 1.25rem;
  color: var(--muted);
  box-shadow: none;
  font-size: 0.86rem;
}

code {
  padding: 0.08em 0.32em;
  border-radius: 5px;
  background: rgba(92, 69, 199, 0.09);
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
}

@media (prefers-color-scheme: dark) {
  :root {
    --ink: #e6eaf3;
    --muted: #aeb7ca;
    --paper: #0b1020;
    --surface: rgba(20, 27, 46, 0.9);
    --line: rgba(183, 197, 225, 0.18);
    --violet: #9c8bf0;
    --teal: #58c9bf;
    --shadow: 0 18px 60px rgba(0, 0, 0, 0.28);
  }
  .candidate-disclaimer,
  .candidate-badge { color: #f2d083; }
}

@media (max-width: 1000px) {
  .frontier-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 780px) {
  .hero { padding-bottom: 4rem; }
  .site-mark,
  .crumbs { margin-bottom: 3.5rem; }
  .family-grid,
  .view-grid,
  .frontier-grid { grid-template-columns: 1fr; }
  .family-grid { margin-top: -1.5rem; }
  h1 { font-size: clamp(2.5rem, 13vw, 4.2rem); }
}