/* LeukemiPrediag — design system
   Serif (Source Serif 4) for headings & long-form copy, sans (Inter) for UI chrome. */

:root {
  --paper: #F3F1EC;
  --paper-2: #EAE6DD;
  --ink: #1E1C19;
  --ink-soft: #5B564C;
  --ink-faint: #8A8577;
  --line: #DCD7CB;
  --amber: #A97426;
  --amber-bright: #E3B45B;
  --dark: #1D1B18;
  --dark-2: #141310;
  --dark-line: #38352E;
  --serif: 'Source Serif 4', Georgia, 'Times New Roman', serif;
  --sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --container: 1120px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--serif);
  font-size: 1.05rem;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}
img { max-width: 100%; display: block; }
a { color: inherit; }
h1, h2, h3, h4 {
  font-family: var(--serif);
  font-weight: 500;
  line-height: 1.15;
  margin: 0 0 0.5em;
  letter-spacing: -0.01em;
}
h1 { font-size: clamp(2.4rem, 5vw + 1rem, 4.3rem); font-weight: 500; }
h2 { font-size: clamp(1.7rem, 2.6vw + 1rem, 2.5rem); }
h3 { font-size: 1.3rem; font-weight: 600; }
p { margin: 0 0 1.1em; color: var(--ink-soft); }
p.lead { font-size: 1.2rem; color: var(--ink); }
strong { color: var(--ink); font-weight: 600; }
.wrap { max-width: var(--container); margin: 0 auto; padding: 0 24px; }

:focus-visible {
  outline: 2px solid var(--amber);
  outline-offset: 3px;
}

/* ---------- UI chrome (sans) ---------- */
.eyebrow, .nav-links a, .btn, .mono, .footer-meta, .stamp-label, .data-label, .badge, .m span {
  font-family: var(--sans);
}
.eyebrow {
  display: inline-block;
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--amber);
  margin-bottom: 1em;
}
.section-dark .eyebrow { color: var(--amber-bright); }

/* ---------- Nav ---------- */
nav {
  border-bottom: 1px solid var(--line);
  background: var(--paper);
  position: sticky;
  top: 0;
  z-index: 40;
}
.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 76px;
}
.logo {
  font-family: var(--serif);
  font-size: 1.15rem;
  font-weight: 600;
  text-decoration: none;
  color: var(--ink);
  letter-spacing: -0.01em;
}
.logo span { color: var(--amber); }
.nav-links {
  list-style: none;
  display: flex;
  align-items: center;
  gap: 2rem;
  margin: 0;
  padding: 0;
}
.nav-links a {
  text-decoration: none;
  color: var(--ink-soft);
  font-size: 0.92rem;
  font-weight: 500;
  transition: color 0.15s ease;
}
.nav-links a:hover, .nav-links a[aria-current="page"] { color: var(--ink); }
.nav-links a.nav-cta {
  color: var(--paper);
  background: var(--ink);
  padding: 0.55rem 1.1rem;
  border-radius: 3px;
}
.nav-links a.nav-cta:hover { background: var(--amber); }
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 40px;
  height: 40px;
  background: none;
  border: 1px solid var(--line);
  border-radius: 4px;
  cursor: pointer;
  padding: 0;
}
.nav-toggle span {
  display: block;
  height: 2px;
  width: 18px;
  margin: 0 auto;
  background: var(--ink);
  transition: transform 0.2s ease, opacity 0.2s ease;
}
.nav-toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ---------- Buttons ---------- */
.btn {
  display: inline-block;
  font-size: 0.95rem;
  font-weight: 600;
  text-decoration: none;
  padding: 0.85rem 1.6rem;
  border-radius: 3px;
  border: 1px solid transparent;
  transition: background 0.15s ease, color 0.15s ease, border-color 0.15s ease;
}
.btn-primary { background: var(--ink); color: var(--paper); }
.btn-primary:hover { background: var(--amber); }
.btn-ghost { border-color: var(--line); color: var(--ink); }
.btn-ghost:hover { border-color: var(--ink); }
.section-dark .btn-ghost { border-color: var(--dark-line); color: var(--paper); }
.section-dark .btn-ghost:hover { border-color: var(--amber-bright); }
.btn-row { display: flex; gap: 1rem; flex-wrap: wrap; margin: 2rem 0; }

/* ---------- Hero ---------- */
.hero { padding: 5rem 0 4rem; }
.hero .lead { max-width: 62ch; }

/* ---------- Sections ---------- */
.section { padding: 4.5rem 0; }
.section-tight { padding: 3rem 0; }
.section-alt { background: var(--paper-2); }
.section-dark {
  background: var(--dark);
  color: var(--paper);
}
.section-dark h1, .section-dark h2, .section-dark h3 { color: var(--paper); }
.section-dark p { color: #C7C2B6; }
.section-dark .wrap { padding-top: 4.5rem; padding-bottom: 4.5rem; }
.section-divider { border: none; border-top: 1px solid var(--line); margin: 0; }
.section-head { max-width: 68ch; margin-bottom: 2.5rem; }

/* ---------- Stat grid ---------- */
.stat-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 2.5rem 3rem;
  margin: 2rem 0;
}
.stat-number {
  font-family: var(--serif);
  font-size: clamp(2.6rem, 4.5vw, 3.6rem);
  color: var(--amber);
  line-height: 1;
  margin-bottom: 0.3em;
}
.stat-label {
  font-family: var(--sans);
  font-weight: 600;
  font-size: 1rem;
  color: var(--ink);
  margin-bottom: 0.4em;
}
.stat-desc { font-size: 0.95rem; color: var(--ink-soft); margin: 0; }

.stat-hero { text-align: left; margin: 1.5rem 0 2.5rem; }
.stat-hero .stat-number { font-size: clamp(3.4rem, 9vw, 6rem); }

/* ---------- Data table ---------- */
.datatable { border-top: 1px solid var(--line); margin: 2rem 0; }
.datatable .row {
  display: flex;
  justify-content: space-between;
  gap: 1.5rem;
  padding: 1.1rem 0;
  border-bottom: 1px solid var(--line);
}
.datatable .row .k {
  font-family: var(--sans);
  color: var(--ink-soft);
  font-size: 0.95rem;
}
.datatable .row .v {
  font-family: var(--serif);
  color: var(--ink);
  text-align: right;
  font-size: 1.02rem;
}
.section-dark .datatable { border-top-color: var(--dark-line); }
.section-dark .datatable .row { border-bottom-color: var(--dark-line); }
.section-dark .datatable .row .k { color: var(--ink-faint); }
.section-dark .datatable .row .v { color: var(--paper); }
.datatable-note { font-size: 0.9rem; color: var(--ink-faint); margin-top: 1rem; }

/* ---------- Cards ---------- */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.5rem;
  margin: 2rem 0;
}
.card {
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 1.6rem;
  background: var(--paper);
}
.card h3 { font-size: 1.05rem; margin-bottom: 0.5em; }
.card p { font-size: 0.95rem; margin: 0; }
.badge {
  display: inline-block;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ink-faint);
  border: 1px solid var(--line);
  border-radius: 2px;
  padding: 0.2rem 0.55rem;
  margin-bottom: 0.9rem;
}

/* ---------- Roadmap / milestones ---------- */
.milestones { border-top: 1px solid var(--line); margin: 2rem 0; }
.milestone {
  display: grid;
  grid-template-columns: 3.5rem 1fr;
  gap: 1.5rem;
  padding: 1.8rem 0;
  border-bottom: 1px solid var(--line);
}
.milestone .n {
  font-family: var(--serif);
  color: var(--amber);
  font-size: 1.4rem;
}
.milestone h3 { margin-bottom: 0.35em; }
.milestone .gate {
  display: inline-block;
  font-family: var(--sans);
  font-size: 0.8rem;
  color: var(--ink-faint);
  margin-top: 0.6rem;
}

/* ---------- Prose section (research page) ---------- */
.prose { max-width: 72ch; }
.prose p { font-size: 1.05rem; }
.toc {
  list-style: none;
  margin: 2rem 0;
  padding: 1.4rem 1.6rem;
  border: 1px solid var(--line);
  border-radius: 4px;
  font-family: var(--sans);
}
.toc li { margin: 0.4rem 0; }
.toc a { text-decoration: none; color: var(--ink-soft); font-size: 0.92rem; }
.toc a:hover { color: var(--amber); }
.toc .toc-title {
  font-family: var(--sans);
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-faint);
  margin-bottom: 0.7rem;
  display: block;
}

/* ---------- Contact card ---------- */
.contact-card {
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 2.2rem;
  background: var(--paper);
  max-width: 480px;
}
.contact-card .row {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.9rem 0;
  border-bottom: 1px solid var(--line);
  font-family: var(--sans);
  font-size: 0.95rem;
}
.contact-card .row:last-child { border-bottom: none; }
.contact-card .row .k { color: var(--ink-faint); }
.contact-card .row a { color: var(--ink); text-decoration: none; font-weight: 600; }
.contact-card .row a:hover { color: var(--amber); }

/* ---------- Footer ---------- */
footer {
  background: var(--dark);
  color: var(--ink-faint);
  padding: 3rem 0 2rem;
}
footer .footer-top {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 2rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid var(--dark-line);
}
footer .footer-brand { font-family: var(--serif); color: var(--paper); font-size: 1.1rem; }
footer .footer-tagline {
  color: var(--ink-faint);
  font-family: var(--sans);
  font-size: 0.85rem;
  max-width: 36ch;
  margin-top: 0.6rem;
}
footer .footer-links {
  list-style: none;
  display: flex;
  gap: 1.6rem;
  margin: 0;
  padding: 0;
  flex-wrap: wrap;
}
footer .footer-links a { color: var(--ink-faint); text-decoration: none; font-size: 0.9rem; }
footer .footer-links a:hover { color: var(--amber-bright); }
.footer-meta { font-size: 0.82rem; margin-top: 1.5rem; letter-spacing: 0.02em; }

/* ---------- Responsive ---------- */
@media (max-width: 767px) {
  .nav-toggle { display: flex; }
  .nav-links {
    position: absolute;
    top: 76px;
    left: 0;
    right: 0;
    background: var(--paper);
    border-bottom: 1px solid var(--line);
    flex-direction: column;
    align-items: flex-start;
    gap: 0;
    padding: 0.5rem 24px 1.2rem;
    display: none;
  }
  .nav-links[data-open="true"] { display: flex; }
  .nav-links li { width: 100%; }
  .nav-links a { display: block; padding: 0.85rem 0; width: 100%; }
  .nav-links a.nav-cta { display: inline-block; width: auto; margin-top: 0.5rem; }
  .hero { padding: 3rem 0 2.5rem; }
  .section { padding: 3rem 0; }
  .milestone { grid-template-columns: 1fr; }
  footer .footer-top { flex-direction: column; }
}

@media (min-width: 1280px) {
  .wrap { padding: 0 32px; }
}