:root {
  --bg: #ffffff;
  --surface: #ffffff;
  --border: #e2e6ea;
  --text: #1a2027;
  --muted: #5b6672;
  --primary: #1f6feb;
  --primary-ink: #ffffff;
  --ok: #1a7f37;
  --ok-bg: #e6f4ea;
  --warn: #9a6700;
  --warn-bg: #fff8e1;
  --bad: #cf222e;
  --bad-bg: #fdecee;
  --radius: 10px;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.06), 0 8px 24px rgba(0, 0, 0, 0.04);
  --mono: ui-monospace, SFMono-Regular, Menlo, monospace;
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f1319;
    --surface: #171c24;
    --border: #262d38;
    --text: #e6eaf0;
    --muted: #9aa4b1;
    --primary: #4c8dff;
    --ok: #4ac26b;
    --ok-bg: #10261a;
    --warn: #e3b341;
    --warn-bg: #2a2410;
    --bad: #ff6b74;
    --bad-bg: #2a1416;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.4);
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: var(--sans);
  background: var(--bg);
  color: var(--text);
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
}

.wrap {
  max-width: 820px;
  margin: 0 auto;
  padding: 32px 20px 80px;
}
.wrap-wide { max-width: 1040px; }

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 28px;
}

.brand {
  font-weight: 700;
  font-size: 1.05rem;
  letter-spacing: -0.01em;
}
.brand a { color: inherit; text-decoration: none; }

.navlinks { display: flex; gap: 8px; }
.navlinks a {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.9rem;
  padding: 6px 10px;
  border-radius: 8px;
}
.navlinks a:hover { background: var(--surface); color: var(--text); }

h1 { font-size: 1.7rem; letter-spacing: -0.02em; margin: 0 0 6px; }
h2 { font-size: 1.15rem; margin: 28px 0 12px; }
.lead { color: var(--muted); margin: 0 0 24px; }

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 22px;
}
.card + .card { margin-top: 16px; }

.menu-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}
@media (max-width: 620px) { .menu-grid { grid-template-columns: 1fr; } }
/* Cards in the menu grid are laid out with `gap`, so cancel the stacked-card top margin. */
.menu-grid .card + .card { margin-top: 0; }

.menu-card {
  display: flex;
  flex-direction: column;
  justify-content: center;
  text-decoration: none;
  color: inherit;
  transition: transform 0.08s ease, border-color 0.15s ease;
}
.menu-card:hover { transform: translateY(-2px); border-color: var(--primary); }
.menu-card .eyebrow { color: var(--primary); font-weight: 600; font-size: 0.8rem; text-transform: uppercase; letter-spacing: 0.04em; }
.menu-card h3 { margin: 0; font-size: 1.2rem; }
.menu-card p { margin: 0; color: var(--muted); font-size: 0.92rem; }

/* Buttons */
.btn {
  appearance: none;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  font: inherit;
  font-weight: 600;
  padding: 10px 16px;
  border-radius: 8px;
  cursor: pointer;
  transition: background 0.12s ease, border-color 0.12s ease;
}
.btn:hover { border-color: var(--primary); }
.btn.primary { background: var(--primary); color: var(--primary-ink); border-color: var(--primary); }
.btn.primary:hover { filter: brightness(1.05); }
.btn.ghost { background: transparent; }
.btn:disabled { opacity: 0.5; cursor: not-allowed; }
.btn-row { display: flex; gap: 10px; flex-wrap: wrap; }

/* Quiz progress */
.progress {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 18px;
  font-size: 0.9rem;
  color: var(--muted);
}
.score-pill {
  font-variant-numeric: tabular-nums;
  font-weight: 700;
  color: var(--text);
  background: var(--surface);
  border: 1px solid var(--border);
  padding: 6px 12px;
  border-radius: 999px;
}
.bar { height: 6px; background: var(--border); border-radius: 999px; overflow: hidden; margin-bottom: 22px; }
.bar > span { display: block; height: 100%; background: var(--primary); width: 0; transition: width 0.3s ease; }

.qtype-label { color: var(--primary); font-weight: 600; font-size: 0.8rem; text-transform: uppercase; letter-spacing: 0.04em; margin-bottom: 10px; }
.qtext { font-size: 1.08rem; white-space: pre-wrap; font-family: Tahoma, Geneva, sans-serif; }
mjx-container[display] { overflow-x: auto; overflow-y: hidden; max-width: 100%; margin: 0.4em 0; }

.answer-row { display: flex; align-items: center; gap: 10px; margin-top: 22px; flex-wrap: wrap; }
.answer-row input[type="text"] {
  font: inherit;
  font-size: 1.1rem;
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--bg);
  color: var(--text);
  width: 160px;
  font-variant-numeric: tabular-nums;
}
.answer-row .unit { color: var(--text); font-weight: 700; }

.feedback { margin-top: 18px; padding: 14px 16px; border-radius: 8px; font-weight: 500; display: none; }
.feedback.show { display: block; }
.feedback.correct { background: var(--ok-bg); color: var(--ok); border: 1px solid var(--ok); }
.feedback.wrong-precision { background: var(--warn-bg); color: var(--warn); border: 1px solid var(--warn); }
.feedback.incorrect { background: var(--bad-bg); color: var(--bad); border: 1px solid var(--bad); }
.feedback .worked { margin-top: 8px; font-weight: 400; color: var(--muted); font-size: 0.9rem; }

/* Quiz layout with question navigator sidebar */
.quiz-layout { display: flex; gap: 24px; align-items: flex-start; }
.sidebar { flex: 0 0 auto; position: sticky; top: 20px; }
.quiz-main { flex: 1 1 auto; min-width: 0; }

.qnav { display: flex; flex-direction: column; gap: 8px; align-items: flex-start; }
.qnav button {
  position: relative;
  min-width: 38px;
  padding: 5px 8px;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  border-radius: 8px;
  font: inherit;
  font-weight: 600;
  font-size: 0.9rem;
  cursor: default;
  display: flex;
  align-items: center;
  justify-content: center;
  font-variant-numeric: tabular-nums;
  transition: border-color 0.12s ease;
}
.qnav button.clickable { cursor: pointer; }
.qnav button.clickable:hover { border-color: var(--primary); }
.qnav button.answered {
  background: color-mix(in srgb, var(--primary) 16%, var(--surface));
  border-color: color-mix(in srgb, var(--primary) 40%, var(--border));
  color: var(--text);
}
.qnav button.correct { background: var(--ok-bg); color: var(--ok); border-color: var(--ok); }
.qnav button.incorrect { background: var(--bad-bg); color: var(--bad); border-color: var(--bad); }
.qnav button.wrong-precision { background: var(--warn-bg); color: var(--warn); border-color: var(--warn); }
.qnav button.current { box-shadow: inset 0 0 0 2px var(--primary); border-color: var(--primary); }
.qnav button.flagged::after {
  content: "⚑";
  position: absolute;
  top: -11px;
  right: -9px;
  font-size: 1.4rem;
  color: var(--bad);
  line-height: 1;
}

.sidebar-legend { margin-top: 16px; display: grid; gap: 7px; font-size: 0.75rem; color: var(--muted); }
.sidebar-legend .k { display: inline-flex; align-items: center; gap: 7px; }
.sidebar-legend .swatch { width: 14px; height: 14px; border-radius: 4px; border: 1px solid var(--border); background: var(--surface); display: inline-flex; align-items: center; justify-content: center; flex: 0 0 auto; }
.sidebar-legend .swatch.current { box-shadow: inset 0 0 0 2px var(--primary); border-color: var(--primary); }
.sidebar-legend .swatch.answered { background: var(--border); }
.sidebar-legend .swatch.flag { border: none; color: var(--bad); font-size: 0.8rem; }

#flagBtn.active { color: var(--bad); border-color: var(--bad); }

@media (max-width: 720px) {
  .quiz-layout { flex-direction: column; }
  .sidebar { position: static; flex-basis: auto; width: 100%; }
  /* Lay the question navigator out horizontally (wrapping) so it fits the screen. */
  .qnav { flex-direction: row; flex-wrap: wrap; }
  .sidebar-legend { grid-auto-flow: column; justify-content: start; gap: 14px; margin-top: 12px; }
}

/* Forms (designer) */
label { display: block; font-weight: 600; font-size: 0.85rem; margin-bottom: 6px; }
input[type="text"], input[type="number"], textarea, select {
  font: inherit;
  width: 100%;
  padding: 9px 11px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--bg);
  color: var(--text);
}
textarea { min-height: 90px; resize: vertical; }
.field { margin-bottom: 14px; }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; }
.grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
@media (max-width: 620px) { .grid-3, .grid-2 { grid-template-columns: 1fr; } }
.hint { color: var(--muted); font-size: 0.82rem; margin-top: 4px; }
.row-head { display: flex; justify-content: space-between; align-items: center; margin: 18px 0 10px; }

.var-row, .form-row {
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 12px;
  margin-bottom: 10px;
  background: var(--bg);
}
.mono { font-family: var(--mono); }
.tag { display: inline-block; font-size: 0.75rem; padding: 2px 8px; border-radius: 999px; background: var(--border); color: var(--muted); }
.divider { height: 1px; background: var(--border); margin: 22px 0; }
.small { font-size: 0.85rem; color: var(--muted); }
.error { color: var(--bad); font-size: 0.85rem; margin-top: 6px; }
.preview { background: var(--bg); border: 1px dashed var(--border); border-radius: 8px; padding: 14px; white-space: pre-wrap; font-size: 0.95rem; }
.type-list-item { display: flex; justify-content: space-between; align-items: center; padding: 10px 12px; border: 1px solid var(--border); border-radius: 8px; margin-bottom: 8px; cursor: pointer; background: var(--bg); }
.type-list-item:hover { border-color: var(--primary); }
.type-list-item.active { border-color: var(--primary); box-shadow: inset 0 0 0 1px var(--primary); }

/* Setup option rows */
.check-row { display: flex; align-items: center; gap: 8px; font-weight: 400; margin-bottom: 8px; }
.check-row input { width: auto; }

/* Timer running low */
#timer.low { color: var(--bad); border-color: var(--bad); }

/* Results review list */
.review-item { border: 1px solid var(--border); border-radius: 8px; padding: 12px 14px; margin-bottom: 10px; background: var(--surface); }
.review-item .head { display: flex; align-items: center; gap: 10px; margin-bottom: 6px; }
.review-item .qno { font-weight: 700; }
.review-item .qsnippet { color: var(--muted); font-size: 0.88rem; white-space: pre-wrap; margin: 4px 0 8px; font-family: Tahoma, Geneva, sans-serif; }
.review-item .answers { font-size: 0.92rem; font-variant-numeric: tabular-nums; }
.badge { font-size: 0.72rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.03em; padding: 3px 9px; border-radius: 999px; }
.badge.correct { background: var(--ok-bg); color: var(--ok); }
.badge.wrong-precision { background: var(--warn-bg); color: var(--warn); }
.badge.incorrect { background: var(--bad-bg); color: var(--bad); }
.badge.flagged-badge { background: var(--bad-bg); color: var(--bad); }