/* Chemistry revision notes: one stylesheet for every page. */

:root {
  --paper: #fbfaf6;
  --paper-2: #f3f1ea;
  --ink: #1f2328;
  --ink-2: #4a5058;
  --ink-3: #6e747c;
  --rule: #e2ded3;
  --accent: #1d6a72;
  --accent-soft: #e3f0ef;

  --define: #2f5f9e;
  --define-bg: #eef3fa;
  --key: #1d6a72;
  --key-bg: #e8f3f1;
  --worked: #5a5f66;
  --worked-bg: #ffffff;
  --trap: #a3482b;
  --trap-bg: #fbefe9;
  --exam: #7a5a12;
  --exam-bg: #fbf4e2;
  --practical: #3e6b2f;
  --practical-bg: #eef5ea;
  --beyond: #6b4f8a;
  --beyond-bg: #f3eff8;
  --answers: #4a5058;
  --answers-bg: #f3f1ea;

  --serif: Charter, 'Bitstream Charter', 'Sitka Text', Cambria, Georgia, serif;
  --sans: 'Segoe UI', system-ui, -apple-system, 'Helvetica Neue', Arial, sans-serif;
  --measure: 42rem;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root {
    --paper: #17191c;
    --paper-2: #1f2226;
    --ink: #e6e3dc;
    --ink-2: #bdb9b0;
    --ink-3: #9a968e;
    --rule: #33363b;
    --accent: #6cc0c6;
    --accent-soft: #1d3234;
    --define: #8db4ea;
    --define-bg: #1c2633;
    --key: #6cc0c6;
    --key-bg: #182c2c;
    --worked: #bdb9b0;
    --worked-bg: #1c1e21;
    --trap: #ee9a7c;
    --trap-bg: #33221c;
    --exam: #e2c070;
    --exam-bg: #2e281a;
    --practical: #9ccc88;
    --practical-bg: #1e2a1b;
    --beyond: #c2a8e6;
    --beyond-bg: #272033;
    --answers: #bdb9b0;
    --answers-bg: #202326;
    color-scheme: dark;
  }
}

* { box-sizing: border-box; }

html { font-size: 106.25%; -webkit-text-size-adjust: 100%; }
@media (max-width: 40rem) { html { font-size: 100%; } }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--serif);
  font-variant-numeric: lining-nums;
  line-height: 1.65;
}
td { font-variant-numeric: lining-nums tabular-nums; }

a { color: var(--accent); text-underline-offset: 0.18em; text-decoration-thickness: 1px; }
a:hover { text-decoration-thickness: 2px; }

/* ---------- frame ---------- */

.site-head {
  font-family: var(--sans);
  font-size: 0.85rem;
  border-bottom: 1px solid var(--rule);
  padding: 0.7rem 1.25rem;
}
.crumbs a { color: var(--ink-2); text-decoration: none; }
.crumbs a:hover { color: var(--accent); }
.crumbs span { color: var(--ink-3); }
.crumbs .sep { margin: 0 0.5rem; color: var(--rule); }

.layout {
  display: grid;
  grid-template-columns: 16rem minmax(0, 1fr);
  gap: 3rem;
  max-width: 68rem;
  margin: 0 auto;
  padding: 2rem 1.25rem 4rem;
}
.layout.no-nav { grid-template-columns: minmax(0, 1fr); max-width: var(--measure); }

.side {
  font-family: var(--sans);
  font-size: 0.85rem;
  line-height: 1.4;
  position: sticky;
  top: 1.5rem;
  align-self: start;
  max-height: calc(100vh - 3rem);
  overflow: auto;
}
.side-title { margin: 0 0 0.8rem; font-weight: 600; }
.side-title a { color: var(--ink); text-decoration: none; }
.side ol, .side ul { list-style: none; margin: 0; padding: 0; }
.side .pages > li > a {
  display: flex;
  gap: 0.6rem;
  padding: 0.35rem 0.5rem;
  border-radius: 6px;
  color: var(--ink-2);
  text-decoration: none;
}
.side .pages > li > a:hover { background: var(--paper-2); color: var(--ink); }
.side .pages > li.here > a { background: var(--accent-soft); color: var(--ink); font-weight: 600; }
.side .n { color: var(--ink-3); min-width: 1.1rem; font-variant-numeric: tabular-nums; }
.side .on-page { margin: 0.2rem 0 0.4rem 2.2rem !important; border-left: 1px solid var(--rule); }
.side .on-page a { display: block; padding: 0.18rem 0.6rem; color: var(--ink-3); text-decoration: none; }
.side .on-page a:hover { color: var(--accent); }
.side .extras { margin-top: 0.9rem !important; padding-top: 0.7rem !important; border-top: 1px solid var(--rule); }
.side .extras a { display: block; padding: 0.3rem 0.5rem; color: var(--ink-2); text-decoration: none; }
.side .extras li.here a { color: var(--ink); font-weight: 600; }

@media (max-width: 56rem) {
  .layout { grid-template-columns: minmax(0, 1fr); gap: 1.5rem; padding-top: 1.25rem; }
  .side { position: static; max-height: none; border: 1px solid var(--rule); border-radius: 10px; padding: 0.8rem; order: 2; }
  .side .on-page { display: none; }
  .page { order: 1; }
}

.page { max-width: var(--measure); min-width: 0; }

.site-foot {
  font-family: var(--sans);
  font-size: 0.78rem;
  color: var(--ink-3);
  text-align: center;
  padding: 2rem 1rem 3rem;
  border-top: 1px solid var(--rule);
}

/* ---------- type ---------- */

h1, h2, h3, h4 { font-family: var(--sans); line-height: 1.25; color: var(--ink); }
h1 { font-size: 2rem; margin: 0.2rem 0 0.6rem; letter-spacing: -0.01em; }
h2 { font-size: 1.35rem; margin: 2.8rem 0 0.8rem; padding-top: 1.2rem; border-top: 1px solid var(--rule); }
h3 { font-size: 1.08rem; margin: 1.8rem 0 0.5rem; }
h4 { font-size: 1rem; margin: 1.4rem 0 0.4rem; }
h2, h3 { scroll-margin-top: 1rem; }

.eyebrow { font-family: var(--sans); font-size: 0.8rem; color: var(--ink-3); margin: 0; letter-spacing: 0.02em; }
.lead { font-size: 1.2rem; color: var(--ink-2); margin: 0 0 0.8rem; }
.meta { font-family: var(--sans); font-size: 0.8rem; color: var(--ink-3); display: flex; flex-wrap: wrap; gap: 0.8rem; align-items: center; margin: 0 0 1rem; }
.before { font-family: var(--sans); font-size: 0.85rem; color: var(--ink-2); }

p, ul, ol { margin: 0 0 1rem; }
li { margin: 0.25rem 0; }
li > p { margin: 0.25rem 0; }
strong { font-weight: 700; }
hr { border: none; border-top: 1px solid var(--rule); margin: 2rem 0; }
sub, sup { line-height: 0; }

code { font-family: Consolas, 'SF Mono', Menlo, monospace; font-size: 0.88em; background: var(--paper-2); padding: 0.08em 0.3em; border-radius: 4px; }

.spec-chips { display: inline-flex; gap: 0.3rem; vertical-align: 0.15em; margin-left: 0.3rem; flex-wrap: wrap; }
.meta .spec-chips { margin-left: 0; }
.spec-chip {
  font-family: var(--sans);
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--accent);
  border: 1px solid currentColor;
  border-radius: 999px;
  padding: 0.05rem 0.45rem;
  white-space: nowrap;
}

/* ---------- maths ---------- */

.katex { font-size: 1.06em; }
.math-display { overflow-x: auto; overflow-y: hidden; padding: 0.2rem 0; margin: 0.8rem 0 1.1rem; }
.math-display .katex-display { margin: 0; }
.math-error { color: var(--trap); }
.math-wide { display: inline-block; max-width: 100%; overflow-x: auto; overflow-y: hidden; vertical-align: bottom; padding: 0.2em 0; }
td .math-wide { max-width: none; }

/* ---------- tables ---------- */

.table-wrap { overflow-x: auto; margin: 0.6rem 0 1.4rem; }
table { border-collapse: collapse; width: 100%; font-size: 0.93rem; line-height: 1.45; }
th, td { text-align: left; vertical-align: top; padding: 0.5rem 0.7rem; border-bottom: 1px solid var(--rule); }
th { font-family: var(--sans); font-size: 0.8rem; font-weight: 600; color: var(--ink-2); border-bottom: 2px solid var(--rule); }
tbody tr:last-child td { border-bottom: none; }
.box table { font-size: 0.9rem; }
@media (max-width: 40rem) {
  table.stack, table.stack tbody, table.stack tr, table.stack td { display: block; width: 100%; }
  table.stack thead { display: none; }
  table.stack tr { border: 1px solid var(--rule); border-radius: 10px; padding: 0.35rem 0.75rem; margin: 0 0 0.7rem; background: var(--paper); }
  table.stack td { border: none; padding: 0.3rem 0; }
  table.stack td + td { border-top: 1px dashed var(--rule); }
  table.stack td[data-label]:not([data-label=""])::before {
    content: attr(data-label);
    display: block;
    font-family: var(--sans);
    font-size: 0.7rem;
    font-weight: 600;
    color: var(--ink-3);
  }
  table.stack td:first-child { font-weight: 600; }
  table.stack td:first-child::before { display: none !important; }
  table.stack .math-wide, table.stack .katex { max-width: 100%; }
  table.stack td .math-wide { max-width: 100%; }
}

table.checklist td.code { font-family: var(--sans); font-weight: 600; color: var(--accent); white-space: nowrap; }
table.checklist td:last-child { font-family: var(--sans); font-size: 0.82rem; min-width: 9rem; }

/* ---------- figures ---------- */

figure { margin: 1.4rem 0 1.6rem; }
figure img {
  display: block;
  max-width: 100%;
  height: auto;
  margin: 0 auto;
  background: #fff;
  border: 1px solid var(--rule);
  border-radius: 10px;
}
figcaption { font-family: var(--sans); font-size: 0.82rem; color: var(--ink-3); margin-top: 0.5rem; text-align: center; }

/* ---------- boxes ---------- */

.box {
  --c: var(--key);
  --bg: var(--key-bg);
  background: var(--bg);
  border-left: 3px solid var(--c);
  border-radius: 0 10px 10px 0;
  padding: 0.75rem 1rem 0.2rem;
  margin: 1.2rem 0 1.4rem;
}
.box-label {
  font-family: var(--sans);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  color: var(--c);
  margin: 0 0 0.35rem;
}
.box-title { font-weight: 600; color: var(--ink); letter-spacing: 0; font-size: 0.95rem; margin-left: 0.5rem; }
.box-title::before { content: '·'; color: var(--c); margin-right: 0.5rem; }
.box-hint { font-weight: 400; color: var(--ink-3); letter-spacing: 0; margin-left: 0.5rem; }
.box-body > :last-child { margin-bottom: 0.8rem; }

.box-define { --c: var(--define); --bg: var(--define-bg); }
.box-key { --c: var(--key); --bg: var(--key-bg); }
.box-trap { --c: var(--trap); --bg: var(--trap-bg); }
.box-exam { --c: var(--exam); --bg: var(--exam-bg); }
.box-practical { --c: var(--practical); --bg: var(--practical-bg); }
.box-beyond { --c: var(--beyond); --bg: var(--beyond-bg); border-left-style: dashed; }
.box-worked, .box-method {
  --c: var(--worked);
  --bg: var(--worked-bg);
  border: 1px solid var(--rule);
  border-radius: 10px;
}
.box-method { --bg: var(--paper-2); }
.box-worked ol, .box-method ol { padding-left: 1.3rem; }
.box-worked li::marker, .box-method li::marker { font-family: var(--sans); font-weight: 700; color: var(--ink-3); }
.box-answers {
  --c: var(--answers);
  --bg: var(--answers-bg);
  border-left: none;
  border-top: 3px double var(--rule);
  border-radius: 0;
  margin-top: 2rem;
  font-size: 0.95rem;
}

/* ---------- indexes ---------- */

.page-list { list-style: none; padding: 0; counter-reset: p; }
.page-list > li { counter-increment: p; padding: 0.8rem 0 0.8rem 2.6rem; border-bottom: 1px solid var(--rule); position: relative; margin: 0; }
.page-list > li::before {
  content: counter(p);
  position: absolute;
  left: 0.2rem;
  top: 0.8rem;
  font-family: var(--sans);
  font-weight: 700;
  color: var(--ink-3);
}
.page-list > li > a { font-family: var(--sans); font-weight: 600; font-size: 1.05rem; }
.page-list p { margin: 0.2rem 0 0; color: var(--ink-2); }
.page-list .meta { margin-top: 0.35rem; }
.topic-pages { font-family: var(--sans); font-size: 0.88rem; columns: 2 16rem; column-gap: 2rem; margin: 0.6rem 0 0; padding-left: 1.2rem; }
.topic-pages li { break-inside: avoid; margin: 0.15rem 0; }
.topic-pages a { font-weight: 400; font-size: inherit; }

.pager { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; margin-top: 3rem; padding-top: 1.2rem; border-top: 1px solid var(--rule); font-family: var(--sans); }
.pager a { display: block; text-decoration: none; padding: 0.7rem 0.9rem; border: 1px solid var(--rule); border-radius: 10px; color: var(--ink); font-weight: 600; font-size: 0.92rem; }
.pager a:hover { border-color: var(--accent); }
.pager a span { display: block; font-size: 0.72rem; font-weight: 400; color: var(--ink-3); }
.pager .next { text-align: right; }

/* ---------- print ---------- */

@media print {
  :root { --paper: #fff; }
  .site-head, .side, .pager, .site-foot { display: none; }
  .layout { display: block; padding: 0; max-width: none; }
  .page { max-width: none; }
  h2 { break-after: avoid; }
  .box, figure, table { break-inside: avoid; }
  .box-answers { break-before: page; }
}