:root {
  --navy: #082b49;
  --navy-2: #0d3d62;
  --teal: #16b8a6;
  --teal-dark: #0c887c;
  --ink: #18324a;
  --muted: #64798a;
  --bg: #f5f9fc;
  --card: #ffffff;
  --line: #dce7ef;
  --soft-teal: #e3f7f3;
  --soft-blue: #eef6fb;
  --soft-amber: #fff7e6;
  --danger: #c84f4f;
  --success: #257b61;
  --shadow: 0 14px 38px rgba(12, 51, 78, .08);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.55;
}
a { color: inherit; text-decoration: none; }
button, input { font: inherit; }
button { color: inherit; }
img, svg { display: block; max-width: 100%; }
[hidden] { display: none !important; }

.container { width: min(1180px, calc(100% - 32px)); margin-inline: auto; }
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  min-height: 72px;
  background: rgba(8, 43, 73, .96);
  color: #fff;
  backdrop-filter: blur(10px);
  border-bottom: 1px solid rgba(255,255,255,.07);
}
.nav-wrap { min-height: 72px; display: flex; align-items: center; gap: 24px; }
.brand { display: flex; align-items: center; gap: 10px; margin-right: auto; }
.brand-mark { width: 40px; height: 40px; border: 2px solid var(--teal); border-radius: 12px; display: grid; place-items: center; font-size: 24px; }
.brand strong { display: block; font-size: 17px; letter-spacing: .2px; }
.brand em { color: #39d5c5; font-style: normal; }
.brand small { display: block; color: #b7c8d6; font-size: 10px; margin-top: 1px; }
.main-nav { display: flex; gap: 20px; font-size: 12px; font-weight: 800; }
.main-nav a { opacity: .88; }
.main-nav a:hover, .main-nav a.is-active { color: #42dece; opacity: 1; }
.menu-toggle { display: none; border: 0; background: transparent; color: #fff; font-size: 25px; cursor: pointer; }

.button { display: inline-flex; align-items: center; justify-content: center; border-radius: 10px; padding: 12px 18px; border: 1px solid var(--line); font-weight: 800; cursor: pointer; transition: transform .15s ease, box-shadow .15s ease, background .15s ease; }
.button:hover { transform: translateY(-1px); }
.button-primary { background: var(--teal); border-color: var(--teal); color: #fff; box-shadow: 0 8px 20px rgba(22,184,166,.18); }
.button-primary:hover { background: #12a996; }
.button-secondary { background: #fff; color: var(--ink); }
.header-cta { padding: 10px 15px; font-size: 12px; }

.hero { background: radial-gradient(circle at 78% 28%, rgba(22,184,166,.10), transparent 28%), linear-gradient(135deg,#edf7fb 0%,#fff 65%); overflow: hidden; }
.hero-grid { min-height: 560px; display: grid; grid-template-columns: 1fr 1.05fr; gap: 54px; align-items: center; padding-block: 65px; }
.eyebrow { color: var(--teal-dark); font-weight: 900; font-size: 12px; letter-spacing: 1.7px; margin: 0 0 12px; }
.hero h1 { margin: 0; color: #102f4b; font-size: clamp(42px, 5vw, 67px); line-height: 1.03; letter-spacing: -2.2px; }
.hero h1 span { color: var(--teal-dark); }
.hero-lead { max-width: 670px; font-size: 17px; line-height: 1.72; color: #536a7b; margin: 22px 0 0; }
.hero-actions { display: flex; gap: 12px; margin-top: 26px; flex-wrap: wrap; }
.trust-row { list-style: none; padding: 0; margin: 24px 0 0; display: flex; flex-wrap: wrap; gap: 14px; color: #557084; font-size: 12px; font-weight: 700; }

.hero-demo { background: #fff; border: 1px solid var(--line); border-radius: 22px; padding: 18px; box-shadow: 0 30px 80px rgba(8,43,73,.12); }
.monitor-head { display: flex; align-items: center; gap: 8px; font-size: 11px; font-weight: 800; color: #577084; }
.monitor-head strong { margin-left: auto; color: var(--teal-dark); }
.status-dot { width: 8px; height: 8px; border-radius: 50%; background: var(--teal); box-shadow: 0 0 0 4px rgba(22,184,166,.12); }
.ecg-grid { margin-top: 16px; height: 190px; display: grid; place-items: center; color: #0d3d62; border-radius: 15px; overflow: hidden; background-color: #fffafa; background-image: linear-gradient(#efdcdc 1px, transparent 1px), linear-gradient(90deg,#efdcdc 1px,transparent 1px), linear-gradient(#f7eeee 1px, transparent 1px), linear-gradient(90deg,#f7eeee 1px,transparent 1px); background-size: 25px 25px,25px 25px,5px 5px,5px 5px; }
.ecg-grid svg { width: 100%; height: 100%; }
.visual-disclaimer { margin: 10px 0 0; font-size: 10px; color: #7c8d99; }
.step-pills { list-style: none; padding: 0; margin: 16px 0 0; display: grid; grid-template-columns: repeat(5,1fr); gap: 7px; }
.step-pills li { font-size: 9px; font-weight: 900; text-align: center; padding: 7px 5px; border-radius: 7px; background: var(--soft-blue); color: #49677d; }

.section { padding: 72px 0; }
.section-tight { padding: 28px 0; }
.section-alt { background: #eef5f9; border-block: 1px solid #e2ebf1; }
.section-heading { display: flex; justify-content: space-between; gap: 30px; align-items: end; margin-bottom: 28px; }
.section-heading h2, .quiz-layout h2, .support-card h2 { margin: 0; font-size: clamp(29px, 3vw, 39px); line-height: 1.15; letter-spacing: -.8px; }
.section-heading > p { max-width: 520px; margin: 0; color: var(--muted); }
.muted { color: var(--muted); }

.value-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 14px; }
.value-card { background: #fff; border: 1px solid var(--line); border-radius: 13px; padding: 19px; }
.value-card span { color: var(--teal-dark); font-size: 11px; font-weight: 900; }
.value-card h3 { margin: 5px 0 4px; }
.value-card p { margin: 0; color: var(--muted); font-size: 13px; }

.lesson-grid { display: grid; grid-template-columns: repeat(4,1fr); gap: 16px; }
.lesson-card, .case-card, .evidence-card, .quiz-card { background: #fff; border: 1px solid var(--line); border-radius: 15px; box-shadow: 0 7px 24px rgba(16,57,84,.04); }
.lesson-card { padding: 22px; display: flex; flex-direction: column; min-height: 265px; }
.lesson-number { font-weight: 900; color: var(--teal-dark); font-size: 11px; }
.lesson-card h3 { margin: 10px 0 6px; line-height: 1.3; }
.term-en { color: #708492; font-size: 12px; display: block; margin-top: 3px; font-weight: 600; }
.lesson-card p { color: var(--muted); font-size: 13px; flex: 1; }
.lesson-meta { display: flex; align-items: center; justify-content: space-between; gap: 9px; margin-top: 15px; }
.text-button { border: 0; background: transparent; color: var(--teal-dark); font-weight: 900; cursor: pointer; padding: 0; }

.badge { display: inline-flex; align-items: center; border-radius: 999px; padding: 5px 8px; font-size: 9px; font-weight: 900; letter-spacing: .3px; }
.badge-verified { background: #e2f5ee; color: #236d58; }
.badge-review { background: var(--soft-amber); color: #916812; }
.badge-category { background: #eaf2fb; color: #32648e; }

.case-toolbar { display: flex; justify-content: space-between; align-items: center; gap: 18px; margin-bottom: 20px; }
.case-filters { display: flex; flex-wrap: wrap; gap: 8px; }
.filter-button { border: 1px solid var(--line); background: #fff; border-radius: 999px; padding: 8px 11px; cursor: pointer; font-size: 10px; font-weight: 900; }
.filter-button.is-active { background: var(--navy); color: #fff; border-color: var(--navy); }
.search-box { width: min(300px,100%); display: flex; align-items: center; gap: 8px; background: #fff; border: 1px solid var(--line); border-radius: 10px; padding: 0 11px; }
.search-box input { width: 100%; border: 0; outline: 0; padding: 10px 0; background: transparent; }
.case-grid { display: grid; grid-template-columns: repeat(3,1fr); gap: 16px; }
.case-card { padding: 18px; cursor: pointer; transition: .15s ease; }
.case-card:hover { transform: translateY(-2px); box-shadow: var(--shadow); border-color: #c9dbe7; }
.case-card-head { display: flex; align-items: start; gap: 12px; justify-content: space-between; }
.case-card h3 { margin: 8px 0 5px; }
.case-card p { margin: 0; color: var(--muted); font-size: 12px; }
.case-visual-placeholder { min-height: 115px; margin: 15px 0; border: 1px dashed #bed0dc; border-radius: 11px; display: grid; place-items: center; text-align: center; padding: 14px; color: #718694; font-size: 11px; background: repeating-linear-gradient(0deg,#fff,#fff 11px,#f6eaeb 12px), repeating-linear-gradient(90deg,transparent,transparent 11px,#f6eaeb 12px); }
.case-footer { display: flex; align-items: center; justify-content: space-between; gap: 10px; font-size: 10px; color: #758896; }

.case-workspace { margin-top: 18px; background: #fff; border: 1px solid var(--line); border-radius: 18px; padding: 26px; box-shadow: var(--shadow); }
.case-title-row { display: flex; justify-content: space-between; gap: 20px; align-items: flex-start; }
.case-title-row h2 { margin: 5px 0 3px; }
.case-source-line { color: var(--muted); font-size: 11px; }
.case-review-banner { margin: 20px 0; padding: 12px 14px; background: #fff8e8; border: 1px solid #f1dca9; border-radius: 10px; color: #796121; font-size: 12px; }
.interpretation-layout { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; }
.ecg-placeholder-large { min-height: 315px; border: 1px dashed #b8ccd8; border-radius: 14px; display: grid; place-items: center; text-align: center; padding: 30px; color: #6e8392; background-color: #fffafa; background-image: linear-gradient(#f0dddd 1px,transparent 1px),linear-gradient(90deg,#f0dddd 1px,transparent 1px); background-size: 15px 15px; }
.interpretation-panel { border: 1px solid var(--line); border-radius: 14px; padding: 18px; }
.interpretation-progress { font-size: 11px; color: var(--teal-dark); font-weight: 900; }
.interpretation-panel h3 { margin: 8px 0; }
.choice-list { display: grid; gap: 8px; margin-top: 14px; }
.choice-button { width: 100%; text-align: left; border: 1px solid var(--line); background: #fff; border-radius: 9px; padding: 11px; cursor: pointer; }
.choice-button:hover { border-color: var(--teal); }
.interpretation-actions { display: flex; gap: 9px; margin-top: 15px; }
.answer-panel { margin-top: 20px; border-top: 1px solid var(--line); padding-top: 20px; }
.answer-grid { display: grid; grid-template-columns: repeat(2,1fr); gap: 10px; }
.answer-item { background: #f7fafc; border: 1px solid var(--line); border-radius: 9px; padding: 11px; }
.answer-item strong { display: block; font-size: 10px; color: var(--teal-dark); text-transform: uppercase; }
.answer-item span { display: block; margin-top: 3px; font-size: 13px; }
.reference-list { padding-left: 18px; color: var(--muted); font-size: 12px; }
.reference-list a { color: var(--teal-dark); text-decoration: underline; }

.quiz-layout { display: grid; grid-template-columns: .72fr 1.28fr; gap: 55px; align-items: start; }
.quiz-card { padding: 24px; min-height: 300px; }
.quiz-top { display: flex; justify-content: space-between; align-items: center; color: var(--teal-dark); font-size: 10px; font-weight: 900; }
.quiz-card h3 { font-size: 20px; margin: 18px 0; }
.quiz-option { display: block; width: 100%; text-align: left; border: 1px solid var(--line); border-radius: 9px; padding: 12px; margin: 8px 0; background: #fff; cursor: pointer; }
.quiz-option:disabled { cursor: default; }
.quiz-option.correct { background: #e7f7f0; border-color: #6ab795; }
.quiz-option.wrong { background: #fff0f0; border-color: #dc8c8c; }
.quiz-explanation { margin-top: 15px; padding: 13px; border-radius: 9px; background: #f3f8fb; color: #4e6779; font-size: 13px; }

.evidence-grid { display: grid; grid-template-columns: repeat(3,1fr); gap: 16px; }
.evidence-card { padding: 22px; }
.evidence-card h3 { margin: 12px 0 7px; }
.evidence-card p { color: var(--muted); font-size: 13px; margin: 0; }
.review-note { margin-top: 18px; background: #fff; border: 1px solid var(--line); border-radius: 12px; padding: 14px 16px; display: flex; gap: 10px; font-size: 12px; }

.support-section { padding-top: 20px; }
.support-card { color: #fff; background: linear-gradient(130deg,var(--navy),var(--navy-2)); border-radius: 22px; padding: 36px; display: grid; grid-template-columns: 1.15fr .85fr; gap: 40px; box-shadow: 0 24px 70px rgba(8,43,73,.20); }
.support-card .eyebrow { color: #47d7c8; }
.support-card p { color: #c7d6e0; }
.roadmap { display: grid; gap: 10px; }
.roadmap div { background: rgba(255,255,255,.07); border: 1px solid rgba(255,255,255,.1); border-radius: 11px; padding: 13px; }
.roadmap strong, .roadmap span { display: block; }
.roadmap strong { color: #51dfd0; font-size: 11px; }
.roadmap span { margin-top: 3px; font-size: 12px; color: #dce7ee; }

.site-footer { margin-top: 70px; background: var(--navy); color: #c7d6df; padding: 32px 0; }
.footer-grid { display: flex; justify-content: space-between; gap: 20px; align-items: end; }
.footer-grid p { margin: 4px 0 0; font-size: 12px; }

.lesson-dialog { width: min(720px, calc(100% - 30px)); border: 0; border-radius: 18px; padding: 28px; color: var(--ink); box-shadow: 0 35px 100px rgba(0,0,0,.25); }
.lesson-dialog::backdrop { background: rgba(5,24,38,.67); backdrop-filter: blur(2px); }
.dialog-close { position: absolute; top: 10px; right: 14px; border: 0; background: transparent; font-size: 28px; cursor: pointer; }
.lesson-dialog h2 { margin: 0; }
.lesson-dialog h4 { margin-bottom: 5px; }
.lesson-dialog ul { color: var(--muted); }

@media (max-width: 980px) {
  .main-nav { display: none; position: absolute; top: 72px; left: 16px; right: 16px; background: var(--navy); border: 1px solid rgba(255,255,255,.1); border-radius: 12px; padding: 14px; flex-direction: column; }
  .main-nav.is-open { display: flex; }
  .menu-toggle { display: block; }
  .header-cta { display: none; }
  .hero-grid { grid-template-columns: 1fr; min-height: auto; }
  .value-grid, .lesson-grid { grid-template-columns: repeat(2,1fr); }
  .case-grid { grid-template-columns: repeat(2,1fr); }
  .interpretation-layout, .quiz-layout, .support-card { grid-template-columns: 1fr; }
}

@media (max-width: 640px) {
  .container { width: min(100% - 22px, 1180px); }
  .hero-grid { padding-block: 47px; gap: 32px; }
  .hero h1 { letter-spacing: -1.3px; }
  .step-pills { grid-template-columns: repeat(2,1fr); }
  .section { padding: 54px 0; }
  .section-heading, .case-toolbar, .footer-grid, .case-title-row { flex-direction: column; align-items: stretch; }
  .value-grid, .lesson-grid, .case-grid, .evidence-grid, .answer-grid { grid-template-columns: 1fr; }
  .search-box { width: 100%; }
  .case-workspace { padding: 18px; }
  .ecg-placeholder-large { min-height: 230px; }
  .support-card { padding: 24px; }
  .review-note { flex-direction: column; }
}