/* glass-lio course: one stylesheet for the home page, lessons, reference cards and glossary. */

:root {
  --bg: #fbfaf7;
  --fg: #1f2328;
  --muted: #5b636d;
  --rule: #e2ded6;
  --panel: #f3f0e9;
  --accent: #1f5fae;
  --good: #1d7a45;
  --good-bg: #e3f3e9;
  --bad: #b3261e;
  --bad-bg: #fbe6e4;
  --code-bg: #efece5;
  --measure: 40rem;
  --side: 15rem;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #15171a;
    --fg: #e6e3dc;
    --muted: #9aa1a9;
    --rule: #2e3237;
    --panel: #1d2024;
    --accent: #7fb0f0;
    --good: #6fcf97;
    --good-bg: #173324;
    --bad: #f28b82;
    --bad-bg: #3a1d1b;
    --code-bg: #22262b;
    color-scheme: dark;
  }
}

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

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

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font: 1.0625rem/1.65 Charter, "Bitstream Charter", "Sitka Text", Cambria, Georgia, serif;
}

main {
  max-width: calc(var(--measure) + var(--side) + 3rem);
  margin: 0 auto;
  padding: 2.5rem 1rem 4rem;
}

/* Text column; the right-hand gutter holds sidenotes on wide screens. */
header.page, article, nav.course, .home-list, footer.site {
  max-width: var(--measure);
}

a { color: var(--accent); text-underline-offset: 0.15em; }
a:hover { text-decoration-thickness: 2px; }

h1, h2, h3 {
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  line-height: 1.25;
  letter-spacing: -0.01em;
}
h1 { font-size: 2.1rem; margin: 0.2rem 0 0.4rem; }
h2 { font-size: 1.35rem; margin: 2.6rem 0 0.6rem; }
h3 { font-size: 1.1rem; margin: 1.8rem 0 0.5rem; }

.kicker, .label {
  font: 600 0.78rem/1.4 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
  margin: 0 0 0.3rem;
}
.subtitle { color: var(--muted); font-size: 1.15rem; margin: 0; }
header.page { border-bottom: 1px solid var(--rule); padding-bottom: 1.2rem; margin-bottom: 1.8rem; }
.lede { font-size: 1.12rem; }

.crumbs {
  font: 0.85rem system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  margin: 0 0 1.5rem;
  max-width: var(--measure);
}
.crumbs a { text-decoration: none; }

code, pre, kbd {
  font-family: ui-monospace, "SFMono-Regular", "JetBrains Mono", Menlo, Consolas, monospace;
  font-size: 0.86em;
}
code { background: var(--code-bg); padding: 0.1em 0.3em; border-radius: 4px; }
pre {
  background: var(--code-bg);
  padding: 0.9rem 1rem;
  border-radius: 8px;
  overflow-x: auto;
  line-height: 1.5;
}
pre code { background: none; padding: 0; font-size: 1em; }

/* Display math: scroll sideways rather than overflow the page on phones. */
.eq { overflow-x: auto; overflow-y: hidden; margin: 1rem 0; padding: 0.1rem 0; }
.katex-display { margin: 0.6rem 0; }
/* KaTeX pins an equation's \tag to the right edge; when the equation is wider than the
   column that edge is inside the maths. Reserve room for the tag and scroll instead. */
.katex-display .katex-html:has(> .tag) { min-width: max-content; padding-right: 3.5em; }

table { border-collapse: collapse; margin: 1.2rem 0; font-size: 0.92rem; display: block; overflow-x: auto; }
th, td { border-bottom: 1px solid var(--rule); padding: 0.45rem 0.6rem; text-align: left; vertical-align: top; }
th { font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif; font-size: 0.85rem; }

/* ---- Sidenotes: inline small print on narrow screens, margin notes on wide ones. */
.sidenote {
  display: block;
  font-size: 0.85rem;
  line-height: 1.5;
  color: var(--muted);
  border-left: 2px solid var(--rule);
  padding-left: 0.7rem;
  margin: 0.5rem 0;
}
@media (min-width: 62rem) {
  article p, article li { position: relative; }
  .sidenote {
    float: right;
    clear: right;
    width: var(--side);
    margin-right: calc(-1 * var(--side) - 2.5rem);
    margin-top: 0.2rem;
    margin-bottom: 1rem;
  }
}

/* ---- Callouts, symbols, source, ask. */
.callout, aside.source, aside.ask {
  background: var(--panel);
  border-radius: 10px;
  padding: 0.9rem 1.1rem;
  margin: 1.6rem 0;
}
.callout > :last-child, aside > :last-child { margin-bottom: 0; }
.callout.interview { border-left: 4px solid var(--accent); }

dl.symbols { display: grid; grid-template-columns: max-content 1fr; gap: 0.35rem 1rem; margin: 1.2rem 0; }
dl.symbols dt { font-weight: 600; }
dl.symbols dd { margin: 0; }
@media (max-width: 30rem) {
  dl.symbols { grid-template-columns: 1fr; }
  dl.symbols dd { margin: 0 0 0.6rem; }
}

/* ---- Quizzes. */
.score:empty { display: none; }
.score {
  font: 600 0.9rem system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  color: var(--muted);
}
.quiz, .recall, .sequence-task, .scatter-explorer {
  border: 1px solid var(--rule);
  border-radius: 10px;
  padding: 1rem 1.1rem;
  margin: 1.6rem 0;
}
.quiz .q, .recall .q { margin-top: 0; }
ol.options { list-style: none; padding: 0; margin: 0.6rem 0 0; display: grid; gap: 0.45rem; }

button {
  font: inherit;
  color: inherit;
  cursor: pointer;
}
button.option {
  width: 100%;
  text-align: left;
  background: var(--bg);
  border: 1px solid var(--rule);
  border-radius: 8px;
  padding: 0.55rem 0.8rem;
}
button.option:hover:not(:disabled) { border-color: var(--accent); }
button.option:disabled { cursor: default; }
button.option.correct { background: var(--good-bg); border-color: var(--good); }
button.option.wrong { background: var(--bad-bg); border-color: var(--bad); }
button.option.correct::after { content: "  ✓"; color: var(--good); font-weight: 700; }
button.option.wrong::after { content: "  ✗"; color: var(--bad); font-weight: 700; }
.explain { margin-top: 0.8rem; }
.explain > :last-child { margin-bottom: 0; }

button.action, .scatter-explorer button {
  background: var(--accent);
  color: var(--bg);
  border: 0;
  border-radius: 8px;
  padding: 0.5rem 0.9rem;
  font: 600 0.92rem system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  margin-top: 0.6rem;
}
button.action.secondary { background: transparent; color: var(--accent); border: 1px solid var(--accent); }

.recall textarea {
  width: 100%;
  min-height: 6.5rem;
  font: 0.95rem/1.5 ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
  color: var(--fg);
  background: var(--bg);
  border: 1px solid var(--rule);
  border-radius: 8px;
  padding: 0.6rem;
  resize: vertical;
}
.answer { margin-top: 0.9rem; border-top: 1px solid var(--rule); padding-top: 0.6rem; }
ul.checklist { list-style: none; padding: 0; }
ul.checklist li { padding-left: 1.7rem; position: relative; cursor: pointer; margin: 0.3rem 0; }
ul.checklist li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.3em;
  width: 1rem;
  height: 1rem;
  border: 1.5px solid var(--muted);
  border-radius: 3px;
}
ul.checklist li.done::before { background: var(--good); border-color: var(--good); }
ul.checklist li.done::after { content: "✓"; position: absolute; left: 0.18rem; top: 0; color: var(--bg); font-size: 0.8rem; font-weight: 700; }

/* ---- Sequence task: tap the steps in order. */
.sequence-task ol.steps { list-style: none; padding: 0; display: grid; gap: 0.45rem; }
.sequence-task ol.steps li button {
  width: 100%;
  text-align: left;
  background: var(--bg);
  border: 1px solid var(--rule);
  border-radius: 8px;
  padding: 0.5rem 0.8rem 0.5rem 2.6rem;
  position: relative;
}
.sequence-task ol.steps li button[data-pick]::before {
  content: attr(data-pick);
  position: absolute;
  left: 0.7rem;
  font-weight: 700;
  color: var(--accent);
}
.sequence-task ol.steps li button.correct { background: var(--good-bg); border-color: var(--good); }
.sequence-task ol.steps li button.wrong { background: var(--bad-bg); border-color: var(--bad); }
.sequence-task .hint { font-size: 0.9rem; color: var(--muted); margin: 0; }

/* ---- Scatter explorer (lesson 7). */
.scatter-explorer .controls { display: grid; gap: 0.5rem; margin: 0.4rem 0 0.8rem; }
.scatter-explorer label {
  display: grid;
  grid-template-columns: 9.5rem 1fr 3rem;
  align-items: center;
  gap: 0.6rem;
  font-size: 0.92rem;
}
.scatter-explorer input[type="range"] { width: 100%; accent-color: var(--accent); }
.scatter-explorer output { text-align: right; font-variant-numeric: tabular-nums; }
.scatter-explorer .bars { display: grid; gap: 0.35rem; margin: 0.6rem 0; }
.scatter-explorer .bar { display: grid; grid-template-columns: 2.2rem 1fr 4.5rem; align-items: center; gap: 0.5rem; font-size: 0.88rem; font-variant-numeric: tabular-nums; }
.scatter-explorer .bar span.track { background: var(--panel); border-radius: 4px; height: 0.8rem; overflow: hidden; }
.scatter-explorer .bar span.fill { display: block; height: 100%; background: var(--accent); }
.scatter-explorer .verdict { font-weight: 600; margin: 0.4rem 0 0; }
.scatter-explorer .verdict.ok { color: var(--good); }
.scatter-explorer .verdict.bad { color: var(--bad); }
@media (max-width: 30rem) {
  .scatter-explorer label { grid-template-columns: 1fr 3rem; }
  .scatter-explorer label span.name { grid-column: 1 / -1; }
}

/* ---- Course navigation and home page. */
nav.course {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 0.6rem 1.5rem;
  border-top: 1px solid var(--rule);
  margin-top: 3rem;
  padding-top: 1.2rem;
  font: 0.95rem system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
}

.home-list { list-style: none; padding: 0; margin: 1.5rem 0; display: grid; gap: 0.8rem; }
.home-list li > a {
  display: block;
  text-decoration: none;
  color: inherit;
  border: 1px solid var(--rule);
  border-radius: 10px;
  padding: 0.9rem 1.1rem;
}
.home-list li > a:hover { border-color: var(--accent); }
.home-list .title { display: block; font: 600 1.1rem/1.3 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif; color: var(--accent); }
.home-list .sub { display: block; color: var(--muted); font-size: 0.97rem; margin-top: 0.15rem; }
.home-list .extra { display: block; font: 0.83rem system-ui, -apple-system, "Segoe UI", Roboto, sans-serif; color: var(--muted); margin-top: 0.35rem; }

footer.site { border-top: 1px solid var(--rule); margin-top: 3rem; padding-top: 1rem; font: 0.88rem system-ui, -apple-system, "Segoe UI", Roboto, sans-serif; color: var(--muted); }

dl.glossary dt { font-weight: 700; margin-top: 1.3rem; scroll-margin-top: 1rem; }
dl.glossary dd { margin: 0.2rem 0 0; }
dl.glossary dt:target { color: var(--accent); }