/* Shared styles for "The Mathematics of Noise" interactive course. */

:root {
  --page: #f9f9f7;
  --surface: #fcfcfb;
  --ink: #0b0b0b;
  --ink-2: #52514e;
  --muted: #898781;
  --grid: #e1e0d9;
  --axis: #c3c2b7;
  --border: rgba(11, 11, 11, 0.10);
  --accent: #2a78d6;
  --accent-2: #1baf7a;
  --warn-bg: #fdf6e7;
  --sans: system-ui, -apple-system, "Segoe UI", sans-serif;
  --serif: "Charter", "Iowan Old Style", Georgia, "Times New Roman", serif;
  --mono: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
}
@media (prefers-color-scheme: dark) {
  :root {
    --page: #0d0d0d;
    --surface: #1a1a19;
    --ink: #f2f1ec;
    --ink-2: #c3c2b7;
    --muted: #898781;
    --grid: #2c2c2a;
    --axis: #383835;
    --border: rgba(255, 255, 255, 0.10);
    --accent: #3987e5;
    --accent-2: #199e70;
    --warn-bg: #26200f;
  }
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--page);
  color: var(--ink);
  font-family: var(--serif);
  font-size: 1.06rem;
  line-height: 1.65;
  text-rendering: optimizeLegibility;
}

/* ---------- header / nav ---------- */
.site-nav {
  position: sticky;
  top: 0;
  z-index: 50;
  background: color-mix(in srgb, var(--page) 88%, transparent);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
  font-family: var(--sans);
  font-size: 0.85rem;
}
.site-nav .nav-inner {
  max-width: 72rem;
  margin: 0 auto;
  padding: 0.55rem 1.2rem;
  display: flex;
  align-items: center;
  gap: 1rem;
}
.site-nav .home {
  font-weight: 650;
  color: var(--ink);
  text-decoration: none;
  white-space: nowrap;
}
.site-nav .chapters {
  display: flex;
  gap: 0.15rem;
  margin-left: auto;
  overflow-x: auto;
}
.site-nav .chapters a {
  color: var(--muted);
  text-decoration: none;
  padding: 0.2rem 0.5rem;
  border-radius: 6px;
  font-variant-numeric: tabular-nums;
}
.site-nav .chapters a:hover { color: var(--ink); background: var(--grid); }
.site-nav .chapters a.current {
  color: var(--accent);
  font-weight: 650;
  background: color-mix(in srgb, var(--accent) 12%, transparent);
}

/* ---------- article layout ---------- */
main {
  max-width: 44rem;
  margin: 0 auto;
  padding: 2.5rem 1.2rem 5rem;
}
.chapter-kicker {
  font-family: var(--sans);
  font-size: 0.8rem;
  font-weight: 650;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
  margin: 0 0 0.4rem;
}
h1 {
  font-family: var(--sans);
  font-size: 2.1rem;
  line-height: 1.15;
  letter-spacing: -0.015em;
  margin: 0 0 0.6rem;
}
.lede {
  font-size: 1.15rem;
  color: var(--ink-2);
  margin: 0 0 2.2rem;
}
h2 {
  font-family: var(--sans);
  font-size: 1.45rem;
  letter-spacing: -0.01em;
  margin: 2.8rem 0 0.8rem;
}
h3 {
  font-family: var(--sans);
  font-size: 1.12rem;
  margin: 2rem 0 0.6rem;
}
p { margin: 0 0 1.1rem; }
a { color: var(--accent); }
strong { font-weight: 650; }
hr { border: none; border-top: 1px solid var(--border); margin: 2.5rem 0; }
ul, ol { padding-left: 1.4rem; }
li { margin-bottom: 0.35rem; }

/* display math breathing room */
.katex-display { margin: 1.4rem 0; overflow-x: auto; overflow-y: hidden; padding: 2px 0; }

/* ---------- interactive demo blocks ---------- */
.demo {
  width: min(60rem, calc(100vw - 2.4rem));
  margin: 2rem 0 2rem calc((100% - min(60rem, 100vw - 2.4rem)) / 2);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1rem 1.2rem 1.2rem;
  font-family: var(--sans);
}
.demo figcaption,
.demo .demo-title {
  font-family: var(--sans);
  font-size: 0.95rem;
  font-weight: 650;
  color: var(--ink);
  margin: 0 0 0.2rem;
}
.demo .demo-note {
  font-size: 0.85rem;
  color: var(--ink-2);
  margin: 0 0 0.7rem;
  font-weight: 400;
}
.controls {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1.4rem;
  align-items: center;
  padding: 0.6rem 0 0.9rem;
}
.ctl {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.82rem;
  color: var(--ink-2);
}
.ctl-label { white-space: nowrap; }
.ctl-value {
  font-variant-numeric: tabular-nums;
  color: var(--ink);
  min-width: 4.5em;
  white-space: nowrap;
}
.ctl input[type="range"] {
  width: 140px;
  accent-color: var(--accent);
}
/* prominent headline result (UI.bigReadout): big number + moving gauge */
.ctl-bigread {
  display: inline-flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 2px;
  min-width: 180px;
}
.bigread-value {
  font-size: 1.3rem;
  font-weight: 650;
  line-height: 1.15;
  font-variant-numeric: tabular-nums;
  color: var(--ink);
  white-space: nowrap;
}
.bigread-bar {
  display: block;
  width: 100%;
  height: 6px;
  border-radius: 3px;
  background: var(--grid);
  overflow: hidden;
}
.bigread-fill {
  display: block;
  height: 100%;
  border-radius: 3px;
  background: var(--accent);
  transition: width 90ms linear;
}
/* two-thumb range slider (UI.range): two native inputs overlaid on a
   custom track; only the thumbs take pointer events */
.ctl-range {
  position: relative;
  width: 170px;
  height: 18px;
  display: inline-block;
}
.ctl-range-track, .ctl-range-fill {
  position: absolute;
  top: 7px;
  height: 4px;
  border-radius: 2px;
}
.ctl-range-track { left: 0; right: 0; background: var(--grid); }
.ctl-range-fill { background: var(--accent); }
.ctl-range input[type="range"] {
  position: absolute;
  left: 0; top: 0;
  width: 100%; height: 18px;
  margin: 0;
  -webkit-appearance: none;
  appearance: none;
  background: transparent;
  pointer-events: none;
}
.ctl-range input[type="range"]::-webkit-slider-runnable-track {
  background: transparent;
  height: 18px;
}
.ctl-range input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  pointer-events: auto;
  width: 14px; height: 14px;
  margin-top: 2px;
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid var(--surface);
  box-shadow: 0 0 0 1px var(--axis);
  cursor: pointer;
}
.ctl-range input[type="range"]::-moz-range-track { background: transparent; }
.ctl-range input[type="range"]::-moz-range-thumb {
  pointer-events: auto;
  width: 10px; height: 10px;
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid var(--surface);
  box-shadow: 0 0 0 1px var(--axis);
  cursor: pointer;
}
.ctl select {
  font: inherit;
  color: var(--ink);
  background: var(--surface);
  border: 1px solid var(--axis);
  border-radius: 6px;
  padding: 0.15rem 0.35rem;
}
.ctl-btn {
  font: inherit;
  font-size: 0.82rem;
  color: var(--ink);
  background: var(--surface);
  border: 1px solid var(--axis);
  border-radius: 7px;
  padding: 0.3rem 0.75rem;
  cursor: pointer;
}
.ctl-btn:hover { border-color: var(--accent); color: var(--accent); }
.plots { display: grid; gap: 0.6rem; }
.plots.two-col { grid-template-columns: 1fr 1fr; }
@media (max-width: 720px) { .plots.two-col { grid-template-columns: 1fr; } }
.plot-canvas { border-radius: 8px; }
/* Pin every canvas to its grid track. Without this, a raw canvas's rendered
   width follows its backing-store width, and any draw code that sizes the
   backing store from clientWidth * devicePixelRatio runs away exponentially
   on dpr > 1 displays until the canvas fails to allocate. */
.plots > * { min-width: 0; }
.plots canvas { display: block; width: 100%; }

/* ---------- callouts ---------- */
.callout {
  font-family: var(--sans);
  font-size: 0.95rem;
  line-height: 1.55;
  border: 1px solid var(--border);
  border-left: 3px solid var(--accent);
  border-radius: 8px;
  background: var(--surface);
  padding: 0.9rem 1.1rem;
  margin: 1.6rem 0;
}
.callout .callout-title {
  font-weight: 700;
  font-size: 0.8rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.35rem;
}
.callout.lab { border-left-color: var(--accent-2); }
.callout.lab .callout-title { color: var(--accent-2); }
.callout.warn { border-left-color: #eda100; }
.callout.warn .callout-title { color: #b07800; }

/* ---------- exercises ---------- */
.exercise {
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--surface);
  margin: 1.4rem 0;
  padding: 0.9rem 1.1rem;
}
.exercise .ex-label {
  font-family: var(--sans);
  font-weight: 700;
  font-size: 0.8rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 0.3rem;
}
.exercise details { margin-top: 0.6rem; font-size: 0.98rem; }
.exercise summary {
  font-family: var(--sans);
  font-size: 0.85rem;
  color: var(--accent);
  cursor: pointer;
  user-select: none;
}
.exercise details[open] summary { margin-bottom: 0.4rem; }

/* ---------- code ---------- */
pre {
  font-family: var(--mono);
  font-size: 0.82rem;
  line-height: 1.55;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 0.9rem 1.1rem;
  overflow-x: auto;
  margin: 1.4rem 0;
}
code {
  font-family: var(--mono);
  font-size: 0.88em;
  background: var(--grid);
  border-radius: 4px;
  padding: 0.08em 0.3em;
}
pre code { background: none; padding: 0; font-size: inherit; }

/* ---------- tables ---------- */
table {
  font-family: var(--sans);
  font-size: 0.88rem;
  border-collapse: collapse;
  margin: 1.4rem 0;
  width: 100%;
}
th, td {
  text-align: left;
  padding: 0.45rem 0.7rem;
  border-bottom: 1px solid var(--grid);
  vertical-align: top;
}
th {
  font-size: 0.78rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--muted);
  border-bottom: 1px solid var(--axis);
}
/* KaTeX (and opt-out spans) inside uppercased chrome must keep their case */
th .katex, th .nocase,
.callout-title .katex, .callout-title .nocase { text-transform: none; letter-spacing: normal; }
td { font-variant-numeric: tabular-nums; }

/* ---------- prev / next footer ---------- */
.pager {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 4rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
  font-family: var(--sans);
  font-size: 0.9rem;
}
.pager a {
  text-decoration: none;
  color: var(--ink);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 0.7rem 1rem;
  max-width: 48%;
  background: var(--surface);
}
.pager a:hover { border-color: var(--accent); }
.pager .dir { font-size: 0.75rem; color: var(--muted); display: block; }
.pager .next { margin-left: auto; text-align: right; }

/* ---------- index page ---------- */
.hero { text-align: left; padding: 1.5rem 0 0.5rem; }
.hero h1 { font-size: 2.6rem; }
.toc {
  list-style: none;
  padding: 0;
  display: grid;
  gap: 0.7rem;
  margin: 2rem 0;
}
.toc a {
  display: block;
  text-decoration: none;
  color: var(--ink);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 0.9rem 1.1rem;
}
.toc a:hover { border-color: var(--accent); }
.toc .toc-num {
  font-family: var(--sans);
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--accent);
  letter-spacing: 0.06em;
}
.toc .toc-title {
  font-family: var(--sans);
  font-weight: 650;
  font-size: 1.05rem;
  display: block;
}
.toc .toc-desc {
  font-size: 0.9rem;
  color: var(--ink-2);
  display: block;
  margin-top: 0.15rem;
}

footer.colophon {
  font-family: var(--sans);
  font-size: 0.8rem;
  color: var(--muted);
  text-align: center;
  padding: 2rem 1rem 3rem;
}