:root {
  --color-border: #d3d6da;
  --color-border-filled: #878a8c;
  --color-text: #1a1a1b;
  --color-muted: #555;
  --color-bg: #ffffff;
  --color-panel: #f6f7f8;
  --color-accent: #3a7ca5;
  --color-wrong: #c0392b;
  --color-right: #2e8b57;
  --color-right-bg: #e8f5ee;
  --color-wrong-bg: #fbeceb;
  /* one color per metric (kept clear of the red/green used for feedback) */
  --color-rec: #1f6fb2;
  --color-prec: #7d3c98;
  --color-acc: #c25e00;
}

* { box-sizing: border-box; }

html { font-size: 18px; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--color-bg);
  color: var(--color-text);
  font-family: "Helvetica Neue", Arial, "Segoe UI", sans-serif;
}

/* sticky footer: main grows to fill short pages, pushing the footer down */
body {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

/* ---------- Header ---------- */

#app-header {
  flex: none;
  border-bottom: 1px solid var(--color-border);
}

.header-inner {
  max-width: 760px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 14px 16px;
}

.header-inner h1 {
  font-size: 1.7rem;
  font-weight: 700;
  letter-spacing: 0.02em;
  margin: 0;
}

.amp { font-weight: 400; color: var(--color-muted); }

.subtitle {
  font-size: 1.05rem;
  font-weight: 400;
  color: var(--color-muted);
  letter-spacing: normal;
}

.lede {
  margin: 4px 0 0;
  font-size: 0.9rem;
  color: var(--color-muted);
}

.record {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  flex: none;
}

.record-label {
  font-size: 0.65rem;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: #888;
  font-weight: 700;
}

.record-value {
  font-size: 1.2rem;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}

.link-btn {
  border: none;
  background: none;
  padding: 0;
  font-family: inherit;
  font-size: 0.75rem;
  color: var(--color-accent);
  cursor: pointer;
}

.link-btn:hover { text-decoration: underline; }

/* ---------- Buttons ---------- */

.btn {
  display: inline-block;
  padding: 10px 18px;
  border-radius: 4px;
  border: 1px solid var(--color-text);
  background: var(--color-text);
  color: white;
  font-weight: 600;
  cursor: pointer;
  font-size: 0.95rem;
  font-family: inherit;
  white-space: nowrap;
}

.btn:hover { opacity: 0.85; }

.btn-secondary {
  background: white;
  color: var(--color-text);
  border: 1px solid var(--color-border-filled);
}

.btn-secondary:hover { background: #f4f4f5; opacity: 1; }

.btn-small { padding: 6px 12px; font-size: 0.82rem; }

/* ---------- Main ---------- */

#app-main {
  width: 100%;
  max-width: 760px;
  margin: 0 auto;
  flex: 1 0 auto;
  padding: 24px 16px 48px;
}

.scenario-card {
  border: 1px solid var(--color-border);
  border-radius: 8px;
  padding: 18px 22px 10px;
  margin-bottom: 26px;
}

.scenario-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 6px;
}

.top-buttons { display: flex; gap: 8px; }

.scenario-id {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: #888;
  font-weight: 700;
}

.scenario-intro {
  font-size: 1.05rem;
  color: var(--color-muted);
  margin: 6px 0 14px;
}

.fact {
  font-size: 1.15rem;
  line-height: 1.45;
  margin: 0 0 12px;
}

/* ---------- Questions ---------- */

.question {
  padding: 16px 0 18px;
  border-top: 1px solid var(--color-border);
}

.q-text {
  font-size: 1.1rem;
  font-weight: 700;
  margin: 0 0 12px;
}

.metric { font-weight: 800; }

.m-rec { color: var(--color-rec); }
.m-prec { color: var(--color-prec); }
.m-acc { color: var(--color-acc); }

.question { border-left: 4px solid transparent; padding-left: 14px; }
.question.q-rec { border-left-color: var(--color-rec); }
.question.q-prec { border-left-color: var(--color-prec); }
.question.q-acc { border-left-color: var(--color-acc); }

.options { display: flex; gap: 10px; flex-wrap: wrap; }

.opt {
  min-width: 96px;
  padding: 10px 18px;
  border: 2px solid var(--color-border-filled);
  border-radius: 6px;
  background: white;
  font-family: inherit;
  font-size: 1rem;
  font-weight: 700;
  color: var(--color-text);
  cursor: pointer;
}

.opt:hover:not(:disabled) { background: #f4f4f5; }
.opt:disabled { cursor: default; opacity: 0.55; }
.opt.correct { border-color: var(--color-right); background: var(--color-right-bg); color: var(--color-right); opacity: 1; }
.opt.wrong { border-color: var(--color-wrong); background: var(--color-wrong-bg); color: var(--color-wrong); opacity: 1; }

.feedback {
  margin-top: 12px;
  background: var(--color-panel);
  border-radius: 6px;
  padding: 10px 14px;
  font-size: 0.95rem;
  line-height: 1.65;
}

.verdict { font-weight: 700; margin-bottom: 4px; }
.verdict.ok { color: var(--color-right); }
.verdict.bad { color: var(--color-wrong); }
.rule { font-family: Georgia, "Times New Roman", serif; font-weight: 600; }
.note { margin-top: 6px; font-weight: 600; color: var(--color-right); }

/* ---------- Summary ---------- */

.summary {
  border-top: 2px solid var(--color-text);
  padding-top: 16px;
  margin-top: 6px;
}

.summary-text { font-size: 1.2rem; font-weight: 700; margin: 0 0 4px; }
.summary h3 { font-size: 1rem; margin: 16px 0 10px; }

.matrices {
  display: flex;
  flex-wrap: wrap;
  gap: 18px;
  margin-bottom: 20px;
}

.matrix {
  border-collapse: collapse;
  font-size: 0.9rem;
}

.matrix caption {
  text-align: left;
  font-weight: 700;
  margin-bottom: 6px;
}

.matrix th, .matrix td {
  border: 1px solid var(--color-border);
  padding: 6px 10px;
  text-align: center;
}

.matrix thead th, .matrix tbody th {
  background: var(--color-panel);
  font-weight: 600;
  font-size: 0.8rem;
}

.matrix td { font-size: 1.05rem; font-weight: 700; font-variant-numeric: tabular-nums; min-width: 70px; }
.matrix td.tp, .matrix td.tn { background: var(--color-right-bg); color: var(--color-right); }

/* ---------- Definitions ---------- */

.defs {
  margin-top: 30px;
  border-top: 1px solid var(--color-border);
  padding-top: 12px;
  font-size: 0.92rem;
}

.defs summary { cursor: pointer; font-weight: 600; color: var(--color-muted); }
.defs dt { font-weight: 700; margin-top: 12px; }
.defs dd { margin: 4px 0 0; line-height: 1.5; }

.formula {
  font-family: Georgia, "Times New Roman", serif;
  background: var(--color-panel);
  border-radius: 4px;
  padding: 6px 10px;
  margin-top: 6px;
  display: inline-block;
}

/* ---------- Footer ---------- */

#app-footer {
  flex: none;
  border-top: 1px solid var(--color-border);
}

.footer-inner {
  max-width: 760px;
  margin: 0 auto;
  padding: 18px 16px 28px;
  font-size: 0.8rem;
  color: #777;
  text-align: center;
}

.footer-inner p { margin: 3px 0; }

@media (max-width: 560px) {
  html { font-size: 16px; }
  .header-inner { flex-wrap: wrap; }
  .record { align-items: flex-start; }
  .opt { flex: 1; min-width: 0; }
  .feedback { overflow-x: auto; }
}
.defs .formula { display: table; }