/* ==========================================================================
   Study Portal — single stylesheet.

   Design notes
   - Tokens on :root, dark mode via prefers-color-scheme. No build step.
   - State is expressed with data-* attributes (data-state, data-verdict) so
     automation asserts on semantics rather than on class names.
   - Animation is opt-out via prefers-reduced-motion and ?noanim=1, which keeps
     automated runs from racing transitions.
   ========================================================================== */

:root {
  --bg: #f7f8fa;
  --surface: #ffffff;
  --surface-2: #f1f3f7;
  --border: #dde1e8;
  --border-strong: #c2c9d4;
  --text: #1a1d23;
  --text-muted: #5b6472;
  --text-faint: #808a99;
  --accent: #1f5fbf;
  --accent-soft: #e8f0fc;
  --accent-text: #16467f;
  --ok: #17794a;
  --ok-soft: #e4f4ec;
  --bad: #b3261e;
  --bad-soft: #fdecea;
  --warn: #8a5a00;
  --warn-soft: #fdf3e0;
  --radius: 10px;
  --radius-sm: 6px;
  --shadow: 0 1px 2px rgba(16, 24, 40, .06), 0 1px 3px rgba(16, 24, 40, .1);
  --mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --maxw: 1120px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #14171c;
    --surface: #1b1f26;
    --surface-2: #22272f;
    --border: #2e343d;
    --border-strong: #414954;
    --text: #e8eaee;
    --text-muted: #a3adba;
    --text-faint: #7d8794;
    --accent: #6aa5f5;
    --accent-soft: #1b2a41;
    --accent-text: #b9d4fb;
    --ok: #5ec48d;
    --ok-soft: #16301f;
    --bad: #f2867c;
    --bad-soft: #3a1c19;
    --warn: #e0b063;
    --warn-soft: #33260f;
    --shadow: 0 1px 2px rgba(0, 0, 0, .4);
  }
}

*, *::before, *::after { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.6;
  color: var(--text);
  background: var(--bg);
  /* Keep the footer at the bottom on short pages (the choosers, empty states)
     instead of leaving a band of dead space beneath it. */
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

main { flex: 1 0 auto; }
.site-footer { flex-shrink: 0; }

/* --- layout ------------------------------------------------------------- */

.wrap { max-width: var(--maxw); margin: 0 auto; padding: 0 20px; }

.site-header {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  position: sticky; top: 0; z-index: 20;
}
.site-header .wrap { display: flex; align-items: center; gap: 20px; min-height: 60px; flex-wrap: wrap; }
.brand { font-weight: 700; font-size: 1.05rem; color: var(--text); text-decoration: none; letter-spacing: -.01em; }
.brand span { color: var(--accent); }
.site-nav { display: flex; gap: 4px; margin-left: auto; flex-wrap: wrap; }
.site-nav a {
  color: var(--text-muted); text-decoration: none; font-size: .9rem; font-weight: 500;
  padding: 7px 11px; border-radius: var(--radius-sm);
}
.site-nav a:hover { background: var(--surface-2); color: var(--text); }
.site-nav a[aria-current="page"] { background: var(--accent-soft); color: var(--accent-text); }

main { padding: 32px 0 64px; }

.site-footer {
  border-top: 1px solid var(--border); background: var(--surface);
  padding: 24px 0; font-size: .82rem; color: var(--text-faint);
}
.site-footer p { margin: 0 0 8px; }
.site-footer a { color: var(--text-muted); }
.site-footer .credit {
  margin-top: 14px; padding-top: 12px;
  border-top: 1px solid var(--border);
}
.site-footer .credit a { color: var(--accent); font-weight: 600; }

/* --- typography --------------------------------------------------------- */

h1 { font-size: 1.7rem; line-height: 1.25; margin: 0 0 8px; letter-spacing: -.02em; }
h2 { font-size: 1.2rem; margin: 32px 0 12px; letter-spacing: -.01em; }
h3 { font-size: 1rem; margin: 20px 0 8px; }
p { margin: 0 0 12px; }
a { color: var(--accent); }
.lede { color: var(--text-muted); font-size: 1.02rem; max-width: 68ch; margin-bottom: 24px; }
.muted { color: var(--text-muted); }
.faint { color: var(--text-faint); font-size: .85rem; }
code, kbd, pre { font-family: var(--mono); }

/* --- cards and grids ---------------------------------------------------- */

.grid { display: grid; gap: 16px; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); }

.card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 18px; box-shadow: var(--shadow);
}
.card h3 { margin-top: 0; }
a.card { text-decoration: none; color: inherit; display: block; transition: border-color .12s, transform .12s; }
a.card:hover { border-color: var(--accent); transform: translateY(-1px); }
.card[aria-disabled="true"] { opacity: .55; }

.badge {
  display: inline-block; font-size: .72rem; font-weight: 700; letter-spacing: .04em;
  text-transform: uppercase; padding: 3px 8px; border-radius: 20px;
  background: var(--surface-2); color: var(--text-muted); border: 1px solid var(--border);
}
.badge[data-tone="accent"] { background: var(--accent-soft); color: var(--accent-text); border-color: transparent; }
.badge[data-tone="ok"] { background: var(--ok-soft); color: var(--ok); border-color: transparent; }
.badge[data-tone="bad"] { background: var(--bad-soft); color: var(--bad); border-color: transparent; }
.badge[data-tone="warn"] { background: var(--warn-soft); color: var(--warn); border-color: transparent; }

.row { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }
.spread { display: flex; align-items: center; justify-content: space-between; gap: 16px; flex-wrap: wrap; }

/* --- forms and buttons -------------------------------------------------- */

label { font-weight: 600; font-size: .9rem; display: block; margin-bottom: 6px; }

input[type="text"], select, input[type="search"] {
  width: 100%; padding: 10px 12px; font: inherit; font-size: .95rem;
  color: var(--text); background: var(--surface);
  border: 1px solid var(--border-strong); border-radius: var(--radius-sm);
}
input:focus-visible, select:focus-visible, button:focus-visible, a:focus-visible, [tabindex]:focus-visible {
  outline: 2px solid var(--accent); outline-offset: 2px;
}
input[aria-invalid="true"] { border-color: var(--bad); }

.field { margin-bottom: 18px; }
.field-hint { font-weight: 400; color: var(--text-faint); font-size: .82rem; margin-top: 5px; }
.field-error { color: var(--bad); font-size: .85rem; font-weight: 600; margin-top: 6px; }
.field-error:empty { display: none; }

button, .btn {
  font: inherit; font-size: .93rem; font-weight: 600; cursor: pointer;
  padding: 10px 16px; border-radius: var(--radius-sm);
  border: 1px solid var(--border-strong); background: var(--surface); color: var(--text);
  text-decoration: none; display: inline-flex; align-items: center; gap: 8px;
}
button:hover, .btn:hover { background: var(--surface-2); }
button[data-variant="primary"], .btn[data-variant="primary"] {
  background: var(--accent); border-color: var(--accent); color: #fff;
}
button[data-variant="primary"]:hover, .btn[data-variant="primary"]:hover { filter: brightness(1.08); }
button[data-variant="danger"] { color: var(--bad); border-color: var(--bad); background: transparent; }
button:disabled { opacity: .5; cursor: not-allowed; }

.checkbox-row { display: flex; align-items: center; gap: 9px; }
.checkbox-row input { width: auto; }
.checkbox-row label { margin: 0; font-weight: 500; }

/* --- exam runner -------------------------------------------------------- */

.exam-bar {
  position: sticky; top: 60px; z-index: 15;
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 12px 16px; margin-bottom: 20px; box-shadow: var(--shadow);
}

.timer { font-family: var(--mono); font-size: 1.35rem; font-weight: 700; font-variant-numeric: tabular-nums; }
.timer[data-tone="warn"] { color: var(--warn); }
.timer[data-tone="danger"] { color: var(--bad); }

.navigator { display: flex; flex-wrap: wrap; gap: 5px; margin-top: 12px; }
.navigator a {
  width: 30px; height: 30px; display: grid; place-items: center;
  font-size: .78rem; font-weight: 600; text-decoration: none;
  border: 1px solid var(--border-strong); border-radius: var(--radius-sm);
  color: var(--text-muted); background: var(--surface);
}
.navigator a[data-state="answered"] { background: var(--accent); border-color: var(--accent); color: #fff; }
.navigator a[data-state="partial"] { background: var(--warn-soft); border-color: var(--warn); color: var(--warn); }

.question {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 20px; margin-bottom: 16px; scroll-margin-top: 150px;
}
.question-head { display: flex; align-items: baseline; gap: 10px; margin-bottom: 12px; flex-wrap: wrap; }
.question-number { font-weight: 700; font-family: var(--mono); color: var(--accent); }
.question-meta { margin-left: auto; display: flex; gap: 6px; flex-wrap: wrap; }

.stem > * { margin: 0 0 12px; }
.stem ul { padding-left: 22px; }
.stem li { margin-bottom: 4px; }
.stem pre {
  background: var(--surface-2); border: 1px solid var(--border);
  border-radius: var(--radius-sm); padding: 12px 14px; margin: 0 0 12px;
  overflow-x: auto; font-size: .87rem; line-height: 1.5;
}
.select-hint { font-weight: 700; font-size: .85rem; color: var(--accent-text); background: var(--accent-soft);
  display: inline-block; padding: 4px 10px; border-radius: 20px; margin-bottom: 12px; }

fieldset.options { border: 0; margin: 0; padding: 0; }
fieldset.options legend { position: absolute; width: 1px; height: 1px; overflow: hidden; clip-path: inset(50%); }

.option {
  display: flex; gap: 12px; align-items: flex-start;
  padding: 12px 14px; margin-bottom: 8px; cursor: pointer;
  border: 1px solid var(--border); border-radius: var(--radius-sm); background: var(--surface);
  /* Reset the global label weight — answer text is body copy, not a label. */
  font-weight: 400;
}
.option:hover { border-color: var(--border-strong); background: var(--surface-2); }
.option input { margin: 3px 0 0; flex: none; width: auto; }
.option .option-key { font-family: var(--mono); font-weight: 700; color: var(--text-muted); flex: none; }
.option[data-selected="true"] { border-color: var(--accent); background: var(--accent-soft); }
.option[data-verdict="correct"] { border-color: var(--ok); background: var(--ok-soft); }
.option[data-verdict="incorrect"] { border-color: var(--bad); background: var(--bad-soft); }
.option[data-verdict="missed"] { border-color: var(--ok); border-style: dashed; }
.option-text { flex: 1; }
.rationale {
  display: block; /* the official rationale reads as its own block, not a run-on */
  font-size: .87rem; color: var(--text-muted); margin-top: 8px;
  padding-left: 11px; border-left: 2px solid var(--border-strong);
}

.limit-note { color: var(--warn); font-size: .85rem; font-weight: 600; }
.limit-note:empty { display: none; }

/* --- results ------------------------------------------------------------ */

.verdict-banner {
  border-radius: var(--radius); padding: 22px; margin-bottom: 24px;
  border: 1px solid var(--border); background: var(--surface);
}
.verdict-banner[data-state="passed"] { border-color: var(--ok); background: var(--ok-soft); }
.verdict-banner[data-state="failed"] { border-color: var(--bad); background: var(--bad-soft); }
.verdict-title { font-size: 1.6rem; font-weight: 800; margin: 0 0 4px; letter-spacing: -.02em; }
.score-big { font-family: var(--mono); font-size: 2.4rem; font-weight: 800; font-variant-numeric: tabular-nums; line-height: 1; }

.stats { display: grid; gap: 12px; grid-template-columns: repeat(auto-fit, minmax(140px, 1fr)); margin-top: 16px; }
.stat { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius-sm); padding: 12px 14px; }
.stat dt { font-size: .76rem; text-transform: uppercase; letter-spacing: .04em; color: var(--text-faint); font-weight: 700; }
.stat dd { margin: 4px 0 0; font-size: 1.25rem; font-weight: 700; font-variant-numeric: tabular-nums; }

table { width: 100%; border-collapse: collapse; font-size: .9rem; }
th, td { text-align: left; padding: 9px 10px; border-bottom: 1px solid var(--border); }
th { font-size: .76rem; text-transform: uppercase; letter-spacing: .04em; color: var(--text-faint); }
td.num, th.num { text-align: right; font-variant-numeric: tabular-nums; }
.table-scroll { overflow-x: auto; }

.meter { height: 7px; border-radius: 4px; background: var(--surface-2); overflow: hidden; min-width: 70px; }
.meter > span { display: block; height: 100%; background: var(--accent); }
.meter[data-tone="ok"] > span { background: var(--ok); }
.meter[data-tone="bad"] > span { background: var(--bad); }

.review-item { border-left: 3px solid var(--border); padding-left: 14px; margin-bottom: 24px; }
.review-item[data-verdict="correct"] { border-left-color: var(--ok); }
.review-item[data-verdict="incorrect"] { border-left-color: var(--bad); }
.review-item[data-verdict="unanswered"] { border-left-color: var(--warn); }

/* --- study -------------------------------------------------------------- */

.chapter { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); margin-bottom: 12px; overflow: hidden; }
.chapter > summary { padding: 14px 18px; cursor: pointer; font-weight: 700; display: flex; gap: 10px; align-items: center; }
.chapter > summary::marker { color: var(--accent); }
.chapter-body { padding: 0 18px 16px; border-top: 1px solid var(--border); }
.lo { display: flex; gap: 12px; padding: 9px 0; border-bottom: 1px dashed var(--border); align-items: baseline; }
.lo:last-child { border-bottom: 0; }
.lo-id { font-family: var(--mono); font-size: .82rem; color: var(--accent); font-weight: 700; flex: none; min-width: 72px; }


.empty { text-align: center; padding: 48px 20px; color: var(--text-muted); }

.notice {
  border: 1px solid var(--border); border-left: 3px solid var(--accent);
  background: var(--surface); border-radius: var(--radius-sm);
  padding: 12px 16px; margin-bottom: 20px; font-size: .9rem;
}
.notice[data-tone="warn"] { border-left-color: var(--warn); background: var(--warn-soft); }
.notice[data-tone="bad"] { border-left-color: var(--bad); background: var(--bad-soft); }

dialog {
  border: 1px solid var(--border); border-radius: var(--radius); padding: 24px;
  background: var(--surface); color: var(--text); max-width: 440px; box-shadow: 0 12px 32px rgba(0,0,0,.24);
}
dialog::backdrop { background: rgba(10, 12, 16, .55); }

.sr-only {
  position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip-path: inset(50%); white-space: nowrap; border: 0;
}

.skip-link {
  position: absolute; left: -9999px; top: 0; background: var(--accent); color: #fff;
  padding: 10px 16px; z-index: 100; border-radius: 0 0 var(--radius-sm) 0;
}
.skip-link:focus { left: 0; }

/* Automated runs must not race transitions. */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: .001ms !important; transition-duration: .001ms !important; }
}
body[data-noanim="true"] *, body[data-noanim="true"] *::before, body[data-noanim="true"] *::after {
  animation: none !important; transition: none !important;
}

@media print {
  .site-header, .site-footer, .exam-bar, button { display: none !important; }
  body { background: #fff; }
}