/* LET or Not — patient education site
   Calm, trustworthy, accessible, mobile-first.
   No external fonts or assets. WCAG 2.1 AA contrast. */

:root {
  --c-bg: #f7faf9;
  --c-surface: #ffffff;
  --c-surface-2: #eef4f3;
  --c-ink: #1a2b2e;
  --c-ink-2: #3b5358;
  --c-muted: #607478;
  --c-line: #d6e0e0;
  --c-brand: #186b6b;        /* deep teal */
  --c-brand-ink: #0d4444;
  --c-brand-soft: #d6ebe9;
  --c-accent: #c2541a;       /* warm rust for hand-raised highlights */
  --c-accent-soft: #fbe6d6;
  --c-up: #186b6b;           /* "pushed toward LET" */
  --c-down: #6b6b6b;         /* neutral push back */
  --c-warn-bg: #fff6e0;
  --c-warn-ink: #4a3500;
  --c-disclaimer-bg: #f1eee6;
  --c-disclaimer-ink: #3a3320;

  --radius: 12px;
  --radius-sm: 8px;
  --shadow: 0 1px 2px rgba(20, 35, 40, 0.05), 0 4px 16px rgba(20, 35, 40, 0.06);

  --maxw: 760px;
  --maxw-wide: 1080px;

  --fs-1: clamp(1.85rem, 2.2vw + 1.2rem, 2.6rem);
  --fs-2: clamp(1.4rem, 1.2vw + 1rem, 1.8rem);
  --fs-3: 1.2rem;
  --fs-body: 1.0625rem; /* ~17px */
  --lh-body: 1.65;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue",
    Arial, sans-serif;
  font-size: var(--fs-body);
  line-height: var(--lh-body);
  color: var(--c-ink);
  background: var(--c-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Skip link */
.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--c-brand);
  color: white;
  padding: 0.6rem 1rem;
  border-radius: 0 0 var(--radius-sm) var(--radius-sm);
  z-index: 1000;
}
.skip-link:focus { left: 0; }

/* Header / nav */
.site-header {
  background: var(--c-surface);
  border-bottom: 1px solid var(--c-line);
  position: sticky;
  top: 0;
  z-index: 50;
}
.site-header .wrap {
  max-width: var(--maxw-wide);
  margin: 0 auto;
  padding: 0.75rem 1rem;
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  align-items: center;
  justify-content: space-between;
}
.brand {
  font-weight: 700;
  color: var(--c-brand-ink);
  font-size: 1.15rem;
  text-decoration: none;
  letter-spacing: -0.01em;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}
.brand-mark {
  width: 28px;
  height: 28px;
  flex: 0 0 28px;
}
.nav {
  display: flex;
  gap: 0.25rem;
  flex-wrap: wrap;
}
.nav a {
  text-decoration: none;
  color: var(--c-ink-2);
  padding: 0.45rem 0.7rem;
  border-radius: var(--radius-sm);
  font-size: 0.97rem;
}
.nav a:hover, .nav a:focus-visible {
  background: var(--c-brand-soft);
  color: var(--c-brand-ink);
}
.nav a[aria-current="page"] {
  color: var(--c-brand-ink);
  background: var(--c-brand-soft);
  font-weight: 600;
}

/* Main / pages */
main {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 2rem 1.1rem 3.5rem;
}
main.wide { max-width: var(--maxw-wide); }

h1, h2, h3 {
  color: var(--c-brand-ink);
  line-height: 1.2;
  letter-spacing: -0.01em;
}
h1 { font-size: var(--fs-1); margin: 0 0 1rem; }
h2 { font-size: var(--fs-2); margin: 2.2rem 0 0.8rem; }
h3 { font-size: var(--fs-3); margin: 1.6rem 0 0.6rem; }

p { margin: 0 0 1rem; }
ul, ol { padding-left: 1.4rem; margin: 0 0 1rem; }
li { margin: 0.35rem 0; }
a { color: var(--c-brand); }
a:hover { color: var(--c-brand-ink); }
strong { color: var(--c-ink); }

/* Lead paragraph */
.lead {
  font-size: 1.15rem;
  color: var(--c-ink-2);
}

/* Hero (home) */
.hero {
  background: linear-gradient(180deg, var(--c-brand-soft) 0%, var(--c-bg) 100%);
  padding: 3rem 1rem 2.5rem;
  text-align: left;
}
.hero .wrap {
  max-width: var(--maxw);
  margin: 0 auto;
  display: grid;
  gap: 1.5rem;
  grid-template-columns: 1fr;
  align-items: center;
}
@media (min-width: 720px) {
  .hero .wrap { grid-template-columns: 1.4fr 1fr; gap: 2.5rem; }
}
.hero h1 { margin-top: 0; }
.hero-visual {
  background: var(--c-surface);
  border-radius: var(--radius);
  padding: 1rem;
  box-shadow: var(--shadow);
}
.hero-visual svg,
.hero-visual img { width: 100%; height: auto; display: block; border-radius: var(--radius-sm); }

/* Cards */
.card {
  background: var(--c-surface);
  border: 1px solid var(--c-line);
  border-radius: var(--radius);
  padding: 1.25rem 1.25rem;
  box-shadow: var(--shadow);
  margin: 1rem 0;
}
.card h2:first-child, .card h3:first-child { margin-top: 0; }

.card-grid {
  display: grid;
  gap: 1rem;
  grid-template-columns: 1fr;
  margin: 1rem 0 1.5rem;
}
@media (min-width: 640px) {
  .card-grid { grid-template-columns: 1fr 1fr; }
}
@media (min-width: 900px) {
  .card-grid.three { grid-template-columns: repeat(3, 1fr); }
}

.card-link {
  display: block;
  text-decoration: none;
  color: inherit;
}
.card-link:hover .card,
.card-link:focus-visible .card {
  border-color: var(--c-brand);
  box-shadow: 0 1px 2px rgba(20, 35, 40, 0.05), 0 6px 22px rgba(24, 107, 107, 0.18);
  transform: translateY(-1px);
}
.card-link .card { transition: box-shadow 0.18s ease, transform 0.18s ease, border-color 0.18s ease; }
.card-link .card-cta {
  color: var(--c-brand);
  font-weight: 600;
  margin-top: 0.5rem;
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
}

/* Buttons */
.btn {
  display: inline-block;
  background: var(--c-brand);
  color: white;
  text-decoration: none;
  padding: 0.75rem 1.25rem;
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: 1rem;
  border: 1px solid var(--c-brand);
  cursor: pointer;
  transition: background 0.15s, transform 0.05s;
}
.btn:hover, .btn:focus-visible {
  background: var(--c-brand-ink);
  border-color: var(--c-brand-ink);
  color: white;
}
.btn:active { transform: translateY(1px); }
.btn.large { font-size: 1.08rem; padding: 0.9rem 1.5rem; }
.btn.secondary {
  background: var(--c-surface);
  color: var(--c-brand-ink);
  border: 1px solid var(--c-brand);
}
.btn.secondary:hover, .btn.secondary:focus-visible {
  background: var(--c-brand-soft);
  color: var(--c-brand-ink);
}

/* Algorithm quiz */
.quiz-progress {
  font-size: 0.95rem;
  color: var(--c-muted);
  margin: 0 0 1rem;
}
.quiz-progress-bar {
  background: var(--c-surface-2);
  height: 8px;
  border-radius: 999px;
  overflow: hidden;
  margin-bottom: 1rem;
}
.quiz-progress-bar > span {
  display: block;
  height: 100%;
  background: var(--c-brand);
  transition: width 0.25s ease;
}
.question {
  background: var(--c-surface);
  border: 1px solid var(--c-line);
  border-radius: var(--radius);
  padding: 1.5rem 1.25rem;
  box-shadow: var(--shadow);
}
.question h2 {
  margin-top: 0;
  font-size: 1.25rem;
  color: var(--c-ink);
}
.options {
  display: flex;
  flex-direction: column;
  gap: 0.55rem;
  margin: 1rem 0 0;
  list-style: none;
  padding: 0;
}
.option {
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  border: 1.5px solid var(--c-line);
  border-radius: var(--radius-sm);
  padding: 0.85rem 1rem;
  cursor: pointer;
  background: var(--c-surface);
  transition: border-color 0.15s, background 0.15s;
}
.option:hover { border-color: var(--c-brand); background: var(--c-brand-soft); }
.option input { margin-top: 0.25rem; accent-color: var(--c-brand); }
.option.dontknow {
  border-style: dashed;
  color: var(--c-ink-2);
}
.quiz-actions {
  display: flex;
  gap: 0.75rem;
  margin-top: 1.25rem;
  flex-wrap: wrap;
}
.quiz-actions .btn[disabled] {
  background: var(--c-line);
  border-color: var(--c-line);
  color: var(--c-muted);
  cursor: not-allowed;
}

/* Result page */
.result-bucket {
  border-radius: var(--radius);
  padding: 1.5rem;
  margin: 1rem 0;
  border: 1px solid var(--c-line);
  background: var(--c-surface);
  box-shadow: var(--shadow);
}
.result-bucket .tag {
  display: inline-block;
  font-size: 0.85rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  padding: 0.25rem 0.6rem;
  border-radius: 999px;
  margin-bottom: 0.5rem;
}
.result-bucket.high { background: linear-gradient(180deg, var(--c-brand-soft), var(--c-surface)); border-color: var(--c-brand); }
.result-bucket.high .tag { background: var(--c-brand); color: white; }
.result-bucket.middle { background: var(--c-warn-bg); border-color: #d8b76a; }
.result-bucket.middle .tag { background: #b08527; color: white; }
.result-bucket.low { background: var(--c-surface-2); }
.result-bucket.low .tag { background: var(--c-muted); color: white; }
.result-bucket h2 { color: var(--c-ink); margin: 0.25rem 0 0.6rem; }

.factor-list {
  list-style: none;
  padding: 0;
  margin: 0.5rem 0 0;
}
.factor-list li {
  border-left: 3px solid var(--c-line);
  padding: 0.45rem 0 0.45rem 0.9rem;
  margin: 0.35rem 0;
}
.factor-list.up li { border-left-color: var(--c-brand); }
.factor-list.down li { border-left-color: var(--c-line); color: var(--c-ink-2); }
.factor-list .qtext { display: block; font-weight: 600; color: var(--c-ink); }
.factor-list .atext { display: block; font-size: 0.95rem; color: var(--c-ink-2); }

.uncertainty-callout {
  background: var(--c-warn-bg);
  border: 1px solid #d8b76a;
  border-radius: var(--radius);
  padding: 1rem 1.1rem;
  color: var(--c-warn-ink);
  margin: 1rem 0;
}
.uncertainty-callout strong { color: var(--c-warn-ink); }

.next-steps {
  background: var(--c-brand-soft);
  border-radius: var(--radius);
  padding: 1rem 1.1rem;
  margin: 1rem 0;
}
.next-steps h3 { margin-top: 0; }

/* Diagrams + figures */
figure {
  margin: 1.5rem 0;
  background: var(--c-surface);
  border: 1px solid var(--c-line);
  border-radius: var(--radius);
  padding: 1rem;
  box-shadow: var(--shadow);
}
figure svg { display: block; width: 100%; height: auto; }
figcaption {
  font-size: 0.95rem;
  color: var(--c-muted);
  margin-top: 0.75rem;
  text-align: center;
}

/* Comparison table (graft types) */
.compare {
  width: 100%;
  border-collapse: collapse;
  margin: 1rem 0;
  font-size: 0.97rem;
}
.compare th, .compare td {
  text-align: left;
  padding: 0.7rem 0.6rem;
  border-bottom: 1px solid var(--c-line);
  vertical-align: top;
}
.compare th {
  background: var(--c-surface-2);
  color: var(--c-ink);
  font-weight: 600;
}
.compare tr:last-child td { border-bottom: none; }
@media (max-width: 600px) {
  .compare, .compare thead, .compare tbody, .compare tr, .compare th, .compare td { display: block; width: 100%; }
  .compare thead { display: none; }
  .compare tr {
    background: var(--c-surface);
    border: 1px solid var(--c-line);
    border-radius: var(--radius-sm);
    padding: 0.5rem;
    margin: 0.6rem 0;
  }
  .compare td { border-bottom: 1px dashed var(--c-line); padding: 0.5rem 0.4rem; }
  .compare td:last-child { border-bottom: none; }
  .compare td::before {
    content: attr(data-label);
    display: block;
    font-weight: 600;
    color: var(--c-muted);
    font-size: 0.85rem;
    margin-bottom: 0.15rem;
  }
}

/* Glossary inline term */
.term {
  border-bottom: 1px dotted var(--c-muted);
  cursor: help;
}

/* References list */
.refs {
  list-style: none;
  padding: 0;
  counter-reset: ref;
}
.refs li {
  counter-increment: ref;
  margin: 0.85rem 0;
  padding-left: 2.4rem;
  position: relative;
  font-size: 0.96rem;
}
.refs li::before {
  content: counter(ref) ".";
  position: absolute;
  left: 0;
  top: 0;
  width: 2rem;
  text-align: right;
  font-weight: 700;
  color: var(--c-brand);
}
.refs a { word-break: break-word; }

/* Footer (disclaimer) */
.site-footer {
  background: var(--c-disclaimer-bg);
  color: var(--c-disclaimer-ink);
  padding: 1.5rem 1rem;
  border-top: 1px solid var(--c-line);
  font-size: 0.95rem;
}
.site-footer .wrap {
  max-width: var(--maxw-wide);
  margin: 0 auto;
}
.site-footer p { margin: 0 0 0.5rem; }
.site-footer .small {
  color: var(--c-muted);
  font-size: 0.85rem;
}

/* Utility */
.center { text-align: center; }
.muted { color: var(--c-muted); }
.cta-row { display: flex; gap: 0.75rem; flex-wrap: wrap; margin-top: 1rem; }

/* Focus styles for all interactive elements */
a:focus-visible, button:focus-visible, input:focus-visible, .option:focus-within {
  outline: 3px solid var(--c-brand);
  outline-offset: 2px;
}

/* Reduce motion */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { transition: none !important; animation: none !important; }
  html { scroll-behavior: auto; }
}

/* Print: friendly result print */
@media print {
  .site-header, .quiz-actions, .nav { display: none !important; }
  body { background: white; }
  .card, .result-bucket, figure { box-shadow: none; }
}