:root {
  color-scheme: light;
  --ink: #162236;
  --muted: #617183;
  --line: #d7e1e4;
  --surface: #ffffff;
  --soft: #f3f7f7;
  --blue: #246a9b;
  --teal: #078c8c;
  --purple: #6d3a91;
  --rose: #b54967;
  --green: #16865c;
  --yellow: #d99819;
  --orange: #dc6f24;
  --red: #bd3f45;
  --navy: #162f52;
  --shadow: 0 18px 48px rgba(22, 34, 54, 0.13);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}
* { box-sizing: border-box; }
body { margin: 0; color: var(--ink); background: linear-gradient(180deg, #f9fbfc 0%, #eaf1f2 100%); }
button, input { font: inherit; }
.topbar {
  position: sticky; top: 0; z-index: 20;
  display: grid; grid-template-columns: auto minmax(220px, 1fr) auto; gap: 16px; align-items: center;
  border-bottom: 1px solid rgba(215,225,228,.88);
  padding: 12px clamp(12px, 3vw, 30px);
  background: rgba(255,255,255,.92); backdrop-filter: blur(16px);
}
.brand-link, .tabs button, .library-link, .control, .answer-button {
  border-radius: 8px; font-weight: 850;
}
.brand-link, .library-link { border: 1px solid var(--line); padding: 8px 10px; color: var(--navy); background: var(--surface); text-decoration: none; }
.title-block { min-width: 0; }
.eyebrow { margin: 0 0 4px; color: var(--teal); font-size: .74rem; font-weight: 850; letter-spacing: .08em; text-transform: uppercase; }
h1, h2, h3, p { letter-spacing: 0; }
h1, h2, h3 { margin: 0; line-height: 1.12; }
h1 { font-size: clamp(1.1rem, 2vw, 1.65rem); }
h2 { font-size: clamp(1.35rem, 3vw, 2.1rem); }
h3 { font-size: 1.05rem; }
p { color: var(--muted); line-height: 1.6; }
.tabs { display: flex; flex-wrap: wrap; gap: 8px; justify-content: flex-end; }
.tabs button { border: 1px solid var(--line); padding: 9px 11px; color: var(--navy); background: var(--soft); cursor: pointer; }
.tabs button.active { color: #fff; background: var(--navy); }
main { width: min(1120px, 100%); margin: 0 auto; padding: 26px clamp(14px, 3vw, 34px) 46px; }
.panel { display: none; }
.panel.active { display: grid; gap: 18px; }
.hero, .card, .flashcard, .question-card, .source-card, .info-card {
  border: 1px solid var(--line); border-radius: 8px; background: var(--surface);
}
.hero { display: grid; grid-template-columns: minmax(0, 1.4fr) minmax(280px, .8fr); gap: 20px; padding: clamp(18px, 3vw, 30px); box-shadow: var(--shadow); }
.metric-grid, .card-grid, .source-grid { display: grid; gap: 14px; }
.metric-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.metric-grid div { border: 1px solid var(--line); border-radius: 8px; padding: 14px; text-align: center; background: #fbfcfc; }
.metric-grid strong { display: block; color: var(--blue); font-size: 1.8rem; }
.metric-grid span { color: var(--muted); font-size: .72rem; font-weight: 850; text-transform: uppercase; }
.card-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.card, .info-card, .source-card, .question-card { padding: 17px; }
.tag { width: fit-content; border-radius: 8px; padding: 5px 8px; color: #0d5c57; background: #dff0ee; font-size: .72rem; font-weight: 850; letter-spacing: .06em; text-transform: uppercase; }
.infograph { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 12px; }
.info-card { display: grid; gap: 10px; min-height: 190px; }
.mini-ecg { width: 100%; height: 74px; }
.traffic { display: grid; gap: 8px; }
.traffic div { border-left: 8px solid var(--green); border-radius: 8px; padding: 10px; background: #f7fbfa; }
.traffic div:nth-child(2) { border-left-color: var(--yellow); }
.traffic div:nth-child(3) { border-left-color: var(--red); }
.flashcard { display: grid; gap: 16px; min-height: 240px; padding: 22px; }
.flash-text { font-size: clamp(1.25rem, 3vw, 1.9rem); color: var(--ink); }
.controls { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; }
.control { border: 1px solid var(--line); padding: 10px 12px; color: var(--navy); background: var(--soft); cursor: pointer; }
.control.primary { color: #fff; background: var(--navy); }
.progress { color: var(--muted); font-weight: 800; }
.answer-list { display: grid; gap: 10px; margin-top: 12px; }
.answer-button { border: 1px solid var(--line); padding: 12px; text-align: left; color: var(--ink); background: #fbfcfc; cursor: pointer; }
.answer-button.correct { border-color: var(--green); background: #e8f6ef; }
.answer-button.incorrect { border-color: var(--red); background: #fbecef; }
.rationale { min-height: 28px; color: var(--muted); font-weight: 750; }
.search { width: min(520px, 100%); border: 1px solid var(--line); border-radius: 8px; padding: 12px; }
.source-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.source-card { display: grid; gap: 8px; }
.source-card a { color: var(--blue); font-weight: 800; }
@media (max-width: 880px) {
  .topbar, .hero, .card-grid, .infograph, .source-grid { grid-template-columns: 1fr; }
  .tabs { justify-content: flex-start; }
}
@media (max-width: 560px) { .metric-grid { grid-template-columns: 1fr; } }