/* Remedial — shared styles for the index and every section page.
   Print rules at the bottom: questions print by default; the answer key prints
   only from the "Print answer key" button (html[data-print="answers"]). */

:root {
  --bg: #f7f5f0; --surface: #ffffff; --surface-2: #f0ede6; --line: #e2ddd2;
  --ink: #1f2328; --ink-2: #57606a; --ink-3: #8b949e;
  --accent: #2563eb; --accent-soft: #e7eefc;
  --ok: #15803d; --ok-soft: #e3f4e8; --bad: #b42318; --bad-soft: #fde8e6; --warn: #a15c07; --warn-soft: #fdf1dc;
  --radius: 12px; --shadow: 0 1px 2px rgba(0,0,0,.05), 0 2px 8px rgba(0,0,0,.04);
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, "PingFang SC", "Noto Sans SC", sans-serif;
  --mono: ui-monospace, SFMono-Regular, Menlo, monospace;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #14161a; --surface: #1c1f24; --surface-2: #23272e; --line: #31363f;
    --ink: #e6e8eb; --ink-2: #a5adb8; --ink-3: #6e7681;
    --accent: #6ea0ff; --accent-soft: #1f2a40;
    --ok: #4ade80; --ok-soft: #15301f; --bad: #f87171; --bad-soft: #3a1c1c; --warn: #fbbf24; --warn-soft: #3a2e14;
    --shadow: none; color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #14161a; --surface: #1c1f24; --surface-2: #23272e; --line: #31363f;
  --ink: #e6e8eb; --ink-2: #a5adb8; --ink-3: #6e7681;
  --accent: #6ea0ff; --accent-soft: #1f2a40;
  --ok: #4ade80; --ok-soft: #15301f; --bad: #f87171; --bad-soft: #3a1c1c; --warn: #fbbf24; --warn-soft: #3a2e14;
  --shadow: none; color-scheme: dark;
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--bg); color: var(--ink); font: 16px/1.55 var(--font); }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
button { font: inherit; color: inherit; cursor: pointer; }
img, svg { max-width: 100%; height: auto; }
h1, h2, h3 { line-height: 1.25; margin: 1.2em 0 .5em; }
h1 { font-size: 1.6rem; margin-top: .3em; }
h2 { font-size: 1.25rem; }
h3 { font-size: 1.05rem; }

.wrap { max-width: 860px; margin: 0 auto; padding: 0 16px; }
.wide { max-width: 1120px; }

/* chips & buttons */
.chip { display: inline-flex; align-items: center; gap: 4px; font-size: .75rem; font-weight: 600; padding: 2px 8px; border-radius: 999px; background: var(--surface-2); color: var(--ink-2); white-space: nowrap; }
.chip.k-guide { background: #e8f0fe; color: #1d4ed8; }
.chip.k-demo { background: #f3e8ff; color: #7e22ce; }
.chip.k-practice { background: #e3f4e8; color: #15803d; }
.chip.k-paper { background: #fdf1dc; color: #a15c07; }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .chip[class*="k-"] { background: var(--surface-2); } }
.btn { display: inline-flex; align-items: center; gap: 6px; border: 1px solid var(--line); background: var(--surface); padding: 6px 12px; border-radius: 8px; font-size: .875rem; font-weight: 600; }
.btn:hover { border-color: var(--ink-3); }
.btn.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
.btn.ghost { background: transparent; }
.btn.sm { padding: 3px 9px; font-size: .8rem; }

/* fractions:  <span class="frac"><b>3</b><b>4</b></span>  or [[3/4]] in question data */
.frac { display: inline-flex; flex-direction: column; vertical-align: middle; text-align: center; font-size: .9em; line-height: 1.1; margin: 0 .1em; }
.frac > b { font-weight: inherit; padding: 0 .15em; }
.frac > b:first-child { border-bottom: 1.5px solid currentColor; }
.mixed { white-space: nowrap; }

/* ---------- section pages ---------- */
.topbar { position: sticky; top: 0; z-index: 20; background: color-mix(in srgb, var(--bg) 88%, transparent); backdrop-filter: blur(8px); border-bottom: 1px solid var(--line); }
.topbar .wrap { display: flex; align-items: center; gap: 8px; min-height: 52px; flex-wrap: wrap; padding-top: 6px; padding-bottom: 6px; }
.topbar .back { font-weight: 700; margin-right: auto; }
.topbar .score { font-size: .85rem; color: var(--ink-2); font-variant-numeric: tabular-nums; }

.sec-head { padding: 20px 0 4px; }
.sec-head .meta { display: flex; flex-wrap: wrap; gap: 6px; align-items: center; color: var(--ink-2); font-size: .85rem; }
.sec-head .summary { color: var(--ink-2); margin: .4em 0 0; }

main.section { padding-bottom: 80px; }
.note, .tip, .warn-box { border-radius: var(--radius); padding: 12px 16px; margin: 16px 0; border: 1px solid var(--line); background: var(--surface); }
.tip { background: var(--accent-soft); border-color: transparent; }
.warn-box { background: var(--warn-soft); border-color: transparent; }
.card { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 16px; box-shadow: var(--shadow); margin: 16px 0; }
.demo { background: var(--surface); border: 1px dashed var(--ink-3); border-radius: var(--radius); padding: 16px; margin: 16px 0; }
.demo-label { font-size: .75rem; font-weight: 700; letter-spacing: .06em; text-transform: uppercase; color: var(--ink-3); margin-bottom: 8px; }
table.t { border-collapse: collapse; margin: 12px 0; }
table.t td, table.t th { border: 1px solid var(--line); padding: 6px 10px; text-align: left; }

.qs-heading { display: flex; align-items: baseline; justify-content: space-between; gap: 12px; }
.q { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 16px 16px 12px; margin: 14px 0; box-shadow: var(--shadow); scroll-margin-top: 70px; }
.q:target { outline: 3px solid var(--accent); outline-offset: 2px; }
.q-head { display: flex; align-items: center; gap: 10px; margin-bottom: 6px; }
.q-n { font-weight: 800; min-width: 1.6em; }
.q-marks { color: var(--ink-3); font-size: .8rem; margin-left: auto; }
.q-diff { color: var(--ink-3); font-size: .7rem; letter-spacing: 1px; }
.q-status { font-size: .85rem; font-weight: 700; }
.q-status.ok { color: var(--ok); } .q-status.bad { color: var(--bad); }
.q-prompt > :first-child { margin-top: 0; } .q-prompt > :last-child { margin-bottom: 0; }
.q-fig { margin: 10px 0; text-align: center; }
.q-part { margin-top: 12px; padding-top: 10px; border-top: 1px dashed var(--line); }
.q-part-label { font-weight: 700; margin-right: 4px; }
.q-opts { list-style: none; padding: 0; margin: 10px 0 0; display: grid; gap: 6px; }
.q-opts button { width: 100%; text-align: left; border: 1px solid var(--line); background: var(--surface); border-radius: 8px; padding: 8px 12px; display: flex; gap: 10px; }
.q-opts button:hover { border-color: var(--ink-3); }
.q-opts button .o-n { font-weight: 700; color: var(--ink-2); }
.q-opts button.picked-ok { background: var(--ok-soft); border-color: var(--ok); }
.q-opts button.picked-bad { background: var(--bad-soft); border-color: var(--bad); }
.q-opts button.is-answer { border-color: var(--ok); }
.q-bracket { display: none; }
.q-input { display: flex; gap: 8px; align-items: center; margin-top: 10px; flex-wrap: wrap; }
.q-input input { font: inherit; padding: 6px 10px; border: 1px solid var(--line); border-radius: 8px; background: var(--bg); color: var(--ink); width: 11em; }
.q-input .unit { color: var(--ink-2); }
.q-fb { font-size: .875rem; font-weight: 600; }
.q-fb.ok { color: var(--ok); } .q-fb.bad { color: var(--bad); } .q-fb.warn { color: var(--warn); }
.q-actions { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 12px; align-items: center; }
.q-answer { margin-top: 10px; padding: 10px 14px; border-radius: 8px; background: var(--ok-soft); }
.q-answer .lbl { font-weight: 700; }
.q-answer .working { margin-top: 6px; }
.q-answer .working > :first-child { margin-top: 0; }
.q-space, .ans-line, .print-only, .answer-key { display: none; }

/* quick-fire items (type "quick") laid out in a grid */
.q-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(230px, 1fr)); gap: 8px; margin: 10px 0 18px; }
.q-quick { display: flex; align-items: center; gap: 6px; margin: 0; padding: 7px 10px; flex-wrap: wrap; min-height: 48px; }
.q-quick .q-n { min-width: 2em; color: var(--ink-3); font-weight: 700; font-size: .85rem; }
.q-quick .qq-p { white-space: nowrap; }
.qq-field { display: inline-flex; align-items: center; gap: 4px; }
.qq-field input { font: inherit; width: 5.6em; padding: 4px 8px; border: 1.5px solid var(--line); border-radius: 7px; background: var(--bg); color: var(--ink); }
.qq-field input:focus { outline: none; border-color: var(--accent); }
.q-quick[data-r="ok"] input { border-color: var(--ok); background: var(--ok-soft); }
.q-quick[data-r="bad"] input { border-color: var(--bad); background: var(--bad-soft); }
.q-quick[data-r="form"] input { border-color: var(--warn); background: var(--warn-soft); }
.qq-field .unit { color: var(--ink-2); }
.qq-st { font-weight: 800; width: 1em; }
.q-quick[data-r="ok"] .qq-st { color: var(--ok); } .q-quick[data-r="bad"] .qq-st { color: var(--bad); } .q-quick[data-r="form"] .qq-st { color: var(--warn); cursor: help; }
.qq-rev { margin-left: auto; border: 1px solid var(--line); background: none; border-radius: 50%; width: 24px; height: 24px; font-size: .75rem; color: var(--ink-3); padding: 0; flex: none; }
.qq-ans { width: 100%; font-size: .85rem; color: var(--ok); font-weight: 700; padding-left: 2.3em; }
.qq-blank { display: none; }
.timer { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; margin: 8px 0 0; font-size: .875rem; }
.timer .clock { font: 700 1.1rem var(--mono); font-variant-numeric: tabular-nums; }
.page-break { height: 0; }

/* ---------- index page ---------- */
.hero { padding: 28px 0 8px; }
.hero h1 { font-size: 1.9rem; margin: 0; }
.hero p { color: var(--ink-2); margin: 4px 0 0; }
.stats { display: flex; gap: 10px; flex-wrap: wrap; margin: 16px 0 6px; }
.stat { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 10px 14px; min-width: 110px; }
.stat b { display: block; font-size: 1.35rem; font-variant-numeric: tabular-nums; }
.stat span { font-size: .78rem; color: var(--ink-2); }
.toolbar { display: flex; gap: 8px; flex-wrap: wrap; align-items: center; margin: 14px 0; }
.search { flex: 1 1 260px; font: inherit; padding: 9px 14px; border: 1px solid var(--line); border-radius: 10px; background: var(--surface); color: var(--ink); }
.tabs { display: flex; gap: 4px; flex-wrap: wrap; }
.tab { border: 1px solid var(--line); background: var(--surface); padding: 6px 12px; border-radius: 999px; font-size: .85rem; font-weight: 600; color: var(--ink-2); }
.tab[aria-pressed="true"] { background: var(--ink); color: var(--bg); border-color: var(--ink); }
.views { display: flex; gap: 2px; border-bottom: 1px solid var(--line); margin: 6px 0 16px; overflow-x: auto; }
.view-btn { border: 0; background: none; padding: 10px 14px; font-weight: 600; color: var(--ink-2); border-bottom: 2px solid transparent; white-space: nowrap; }
.view-btn[aria-pressed="true"] { color: var(--ink); border-bottom-color: var(--accent); }
.subject-block { margin: 8px 0 28px; }
.subject-title { display: flex; align-items: center; gap: 10px; margin: 0 0 10px; font-size: 1.2rem; }
.dot { width: 10px; height: 10px; border-radius: 50%; display: inline-block; flex: none; }
.strand { margin: 14px 0; }
.strand-name { font-size: .78rem; font-weight: 700; letter-spacing: .05em; text-transform: uppercase; color: var(--ink-3); margin: 0 0 6px; }
.topic { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); margin: 8px 0; overflow: hidden; }
.topic > summary { list-style: none; cursor: pointer; padding: 12px 14px; display: flex; gap: 10px; align-items: center; }
.topic > summary::-webkit-details-marker { display: none; }
.topic > summary::before { content: "▸"; color: var(--ink-3); transition: transform .15s; }
.topic[open] > summary::before { transform: rotate(90deg); }
.topic-name { font-weight: 700; }
.topic-count { margin-left: auto; font-size: .8rem; color: var(--ink-3); white-space: nowrap; }
.topic-body { padding: 0 14px 12px; }
.topic-summary { color: var(--ink-2); font-size: .9rem; margin: 0 0 8px; }
.empty-topics { color: var(--ink-3); font-size: .85rem; }
.empty-topics span { display: inline-block; margin: 2px 8px 2px 0; }
.sec-row { display: flex; gap: 10px; align-items: center; padding: 9px 0; border-top: 1px solid var(--line); }
.sec-row:first-child { border-top: 0; }
.sec-row .title { font-weight: 600; }
.sec-row .sub { font-size: .8rem; color: var(--ink-3); }
.sec-row .right { margin-left: auto; text-align: right; font-size: .8rem; color: var(--ink-2); white-space: nowrap; }
.progress { height: 5px; background: var(--surface-2); border-radius: 3px; width: 70px; overflow: hidden; display: inline-block; vertical-align: middle; }
.progress > i { display: block; height: 100%; background: var(--ok); }
.list { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 2px 14px; }
.q-row { display: grid; grid-template-columns: auto 1fr auto; gap: 10px; padding: 10px 0; border-top: 1px solid var(--line); align-items: start; }
.q-row:first-child { border-top: 0; }
.q-row .qtext { font-size: .92rem; }
.q-row .qmeta { font-size: .76rem; color: var(--ink-3); margin-top: 2px; }
.q-row .mark { font-size: .85rem; font-weight: 700; }
.filters { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 10px; }
.filters select { font: inherit; font-size: .85rem; padding: 6px 8px; border-radius: 8px; border: 1px solid var(--line); background: var(--surface); color: var(--ink); }
table.papers { width: 100%; border-collapse: collapse; background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; }
table.papers th, table.papers td { padding: 10px 12px; text-align: left; border-top: 1px solid var(--line); font-size: .9rem; }
table.papers th { background: var(--surface-2); font-size: .78rem; text-transform: uppercase; letter-spacing: .04em; color: var(--ink-2); border-top: 0; }
.panel { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 14px 16px; margin: 12px 0; }
.panel h3 { margin: 0 0 8px; }
.wa { display: flex; gap: 10px; padding: 6px 0; border-top: 1px solid var(--line); align-items: baseline; }
.wa:first-of-type { border-top: 0; }
.wa .st { font-size: .72rem; font-weight: 700; padding: 1px 8px; border-radius: 999px; white-space: nowrap; }
.st-weak { background: var(--bad-soft); color: var(--bad); } .st-improving { background: var(--warn-soft); color: var(--warn); } .st-secure { background: var(--ok-soft); color: var(--ok); }
.empty { text-align: center; padding: 40px 16px; color: var(--ink-2); border: 1px dashed var(--line); border-radius: var(--radius); }
.muted { color: var(--ink-3); }
.footer { color: var(--ink-3); font-size: .8rem; padding: 30px 0 40px; }
mark { background: #fde68a; color: inherit; border-radius: 2px; }

@media (max-width: 560px) {
  .sec-row { flex-wrap: wrap; }
  .sec-row > .dot { display: none; }
  .stats { display: grid; grid-template-columns: repeat(3, 1fr); gap: 6px; }
  .stat { min-width: 0; padding: 8px 10px; }
  .stat b { font-size: 1.1rem; }
  .sec-row .right { margin-left: 0; text-align: left; width: 100%; }
  table.papers .hide-sm { display: none; }
}

/* ---------- print ---------- */
@media print {
  @page { margin: 14mm 14mm 16mm; }
  :root { --ink: #000; --ink-2: #222; --ink-3: #555; --line: #999; --surface: #fff; --bg: #fff; color-scheme: light; }
  body { background: #fff; color: #000; font-size: 11.5pt; line-height: 1.45; }
  .wrap { max-width: none; padding: 0; }
  main.section { padding-bottom: 0; }
  .topbar, .screen-only, .q-actions, .q-status, .q-input, .q-fb, .q-answer, .q-diff, .demo, .no-print { display: none !important; }
  .print-only { display: block; }
  span.print-only { display: inline; }
  a { color: #000; }
  .sec-head { padding-top: 0; }
  .sec-head .meta .chip { background: none; padding: 0; border: 0; }
  .print-header { display: flex !important; justify-content: space-between; gap: 16px; border-bottom: 1px solid #000; padding-bottom: 6px; margin-bottom: 10px; font-size: 10.5pt; }
  .print-header span { flex: none; white-space: nowrap; }
  .q { border: 0; box-shadow: none; border-radius: 0; padding: 8px 0 4px; margin: 0 0 10px; break-inside: avoid; page-break-inside: avoid; }
  .q:target { outline: 0; }
  .q-part { border-top: 0; padding-top: 4px; }
  .q-opts { display: grid; grid-template-columns: 1fr 1fr; gap: 2px 20px; }
  .q-opts.long { grid-template-columns: 1fr; }
  .q-opts.tiny { grid-template-columns: repeat(4, 1fr); }
  .q-opts button { border: 0; padding: 2px 0; background: none !important; }
  .q-bracket { display: block; text-align: right; font-size: 11pt; margin-top: 2px; }
  .q-space { display: block; }
  .ans-line { display: flex; justify-content: flex-end; gap: 6px; margin-top: 6px; font-size: 11pt; }
  .ans-line i { display: inline-block; width: 42mm; border-bottom: 1px solid #000; }
  .card, .note, .tip, .warn-box { border: 1px solid #999; background: none; box-shadow: none; break-inside: avoid; }
  h1 { font-size: 16pt; } h2 { font-size: 13pt; break-after: avoid; }

  .q-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 3mm 8mm; margin: 2mm 0 6mm; }
  .q-quick { padding: 0; min-height: 0; margin: 0; break-inside: avoid; flex-wrap: nowrap; }
  .q-quick .q-n { color: #000; font-size: 10pt; }
  .qq-field input, .qq-rev, .qq-st, .qq-ans { display: none !important; }
  .qq-blank { display: inline-block; width: 20mm; border-bottom: 1px solid #000; height: 1.1em; }
  .page-break { break-before: page; page-break-before: always; }
  .h2-print-tight { margin-top: 4mm; }

  /* "Print answer key" — only the key, on its own pages */
  html[data-print="answers"] body > *:not(.answer-key) { display: none !important; }
  html[data-print="answers"] .answer-key { display: block !important; }
}
.answer-key h1 { font-size: 15pt; margin-top: 0; }
.answer-key .ak-item { break-inside: avoid; page-break-inside: avoid; border-bottom: 1px solid #bbb; padding: 6px 0 8px; }
.answer-key .ak-n { font-weight: 800; margin-right: 6px; }
.answer-key .ak-ans { font-weight: 700; }
.answer-key .working { margin: 4px 0 0 1.8em; font-size: 10.5pt; }
.answer-key .working > :first-child { margin-top: 0; } .answer-key .working > :last-child { margin-bottom: 0; }
.answer-key .ak-part { margin-left: 1.8em; }
.answer-key .ak-group { font-size: 12pt; margin: 10px 0 4px; }
.answer-key .ak-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 2px 10px; font-size: 10.5pt; padding-bottom: 6px; border-bottom: 1px solid #bbb; }