@import url("https://fonts.googleapis.com/css2?family=IBM+Plex+Mono:ital,wght@0,400;0,500;1,400&family=Instrument+Serif:ital@0;1&family=Inter:ital,opsz,wght@0,14..32,400;0,14..32,500;0,14..32,600;1,14..32,400;1,14..32,500&display=swap");

*,
*::before,
*::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg: #f6f3ed;
  --paper: #eeeae2;
  --line: #ddd8ce;
  --ink: #161513;
  --body: #3c3a36;
  --muted: #5c5953;
  --faint: #7a766e;
  --accent: #a83c26;
  --mark: #a83c26;
  --focus: #161513;
  --display: "Instrument Serif", Georgia, "Times New Roman", serif;
  --sans: "Inter", ui-sans-serif, system-ui, -apple-system, "Segoe UI", sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, "SFMono-Regular", Menlo, monospace;
  --gutter: 1.15rem;
  --page: 100%;
  --prose: clamp(42ch, 14ch + 40vw, 76ch);
  --space: 1.35em;
  --radius: 2px;
  --type: 1.0625rem;
  --leading: 1.62;
}

/* Phone → tablet → laptop → wide: type and shell grow with the viewport. */
@media (min-width: 480px) {
  :root {
    --gutter: clamp(1.25rem, 4.5vw, 2.5rem);
    --type: 1.075rem;
  }
}

@media (min-width: 720px) {
  :root {
    --gutter: clamp(1.6rem, 5vw, 3.25rem);
    --type: 1.1rem;
    --leading: 1.64;
  }
}

@media (min-width: 960px) {
  :root {
    --gutter: clamp(2rem, 5.5vw, 4.25rem);
    --type: 1.125rem;
  }
}

@media (min-width: 1400px) {
  :root {
    --gutter: clamp(2.25rem, 6vw, 5.5rem);
    --type: 1.175rem;
    --leading: 1.65;
  }
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 5rem;
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

body {
  position: relative;
  background-color: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  font-optical-sizing: auto;
  font-size: var(--type);
  font-weight: 400;
  line-height: var(--leading);
  font-feature-settings: "kern" 1, "liga" 1, "calt" 1, "cv11" 1;
  font-synthesis: none;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  overflow-x: clip;
}

/* Faint paper grain. Opaque specks, very low layer opacity. */
body::before { content: none; }
body::after { content: none; }

.grain-bg {
  position: absolute;
  left: 0;
  top: 0;
  z-index: 0;
  pointer-events: none;
  opacity: 1;
}
body.home-page .grain-bg {
  position: fixed;
  inset: 0;
  width: 100%;
  height: 100%;
}

:focus-visible {
  outline: 2px solid var(--focus);
  outline-offset: 3px;
}

.skip {
  position: absolute;
  left: var(--gutter);
  top: -4rem;
  z-index: 200;
  background: var(--ink);
  color: var(--bg);
  font-family: var(--sans);
  font-size: 0.9rem;
  padding: 0.55rem 0.8rem;
}
.skip:focus { top: 1rem; }

.progress {
  position: fixed;
  top: 0;
  left: 0;
  height: 2px;
  width: 0;
  background: var(--accent);
  z-index: 120;
  pointer-events: none;
}

.wrap {
  position: relative;
  z-index: 1;
  width: 100%;
  max-width: none;
  margin-inline: 0;
  padding-left: max(var(--gutter), env(safe-area-inset-left, 0px));
  padding-right: max(var(--gutter), env(safe-area-inset-right, 0px));
}

a {
  color: var(--accent);
  text-decoration-thickness: 1px;
  text-underline-offset: 0.16em;
}
a:hover { text-decoration-thickness: 2px; }

.site-nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 1.15rem 0 0.85rem;
  border-bottom: 1px solid var(--line);
  font-family: var(--mono);
  font-size: 0.78rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}
.site-nav a { color: var(--ink); text-decoration: none; }
.site-nav a:hover { color: var(--accent); }

.toc {
  position: sticky;
  top: 2px;
  z-index: 90;
  margin: 0 calc(var(--gutter) * -1);
  padding: 0.45rem var(--gutter) 0.35rem;
  background: color-mix(in srgb, var(--bg) 92%, transparent);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid transparent;
}
.toc.is-stuck { border-bottom-color: var(--line); }
.toc-list {
  display: flex;
  gap: 0 1.15rem;
  overflow-x: auto;
  list-style: none;
  scrollbar-width: thin;
  counter-reset: sec;
  -webkit-overflow-scrolling: touch;
}
.toc a {
  display: inline-flex;
  align-items: center;
  min-height: 2.5rem;
  color: var(--muted);
  text-decoration: none;
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.01em;
  white-space: nowrap;
  border-bottom: 1px solid transparent;
}
.toc li { counter-increment: sec; }
.toc a::before {
  content: counter(sec, decimal-leading-zero) "  ";
  color: var(--faint);
  font-variant-numeric: tabular-nums;
}
.toc a:hover,
.toc a[aria-current="true"] {
  color: var(--ink);
  border-bottom-color: var(--ink);
}

header.home {
  display: grid;
  gap: 1.1rem 0;
  padding: clamp(2.75rem, 10vh, 7rem) 0 clamp(2rem, 5vh, 3.5rem);
}
header.home h1 {
  font-family: var(--display);
  font-weight: 400;
  font-size: clamp(3.1rem, 1.6rem + 7vw, 8.5rem);
  letter-spacing: -0.035em;
  line-height: 0.92;
  color: var(--ink);
  font-synthesis: none;
  max-width: none;
}
header.home .lead {
  font-size: clamp(1rem, 0.92rem + 0.35vw, 1.2rem);
  color: var(--muted);
  max-width: 42rem;
  margin-top: 0.25rem;
  line-height: 1.5;
}

@media (min-width: 900px) {
  header.home {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, 1fr);
    column-gap: clamp(2.5rem, 7vw, 8rem);
    align-items: end;
    min-height: min(48vh, 26rem);
  }
  .kicker { grid-column: 1; grid-row: 1; }
  header.home h1 { grid-column: 1; grid-row: 2; }
  header.home .lead {
    grid-column: 2;
    grid-row: 1 / 3;
    align-self: end;
    margin-top: 0;
    max-width: none;
  }
  .home-focus {
    grid-column: 2;
    grid-row: 3;
  }
}

.kicker {
  font-family: var(--mono);
  font-size: 0.78rem;
  letter-spacing: 0.03em;
  color: var(--muted);
  margin: 0 0 0.85rem;
}
.home-focus {
  font-family: var(--mono);
  font-size: 0.78rem;
  color: var(--faint);
  margin-top: 1.15rem;
  letter-spacing: 0.02em;
  line-height: 1.55;
}

.writing-label {
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 2.25rem 0 0;
  padding-bottom: 0.65rem;
  border-bottom: 1px solid var(--line);
}

.note-list {
  list-style: none;
  padding: 0 0 5.5rem;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 28rem), 1fr));
  column-gap: clamp(2rem, 5vw, 5rem);
}
.note-list li { padding: 1.35rem 0; border-bottom: 1px solid var(--line); }
.note-list a.title {
  text-decoration: none;
  font-family: var(--display);
  font-size: clamp(1.45rem, 1.15rem + 1.1vw, 2.05rem);
  font-weight: 400;
  letter-spacing: -0.02em;
  color: var(--ink);
  display: block;
  line-height: 1.18;
  text-wrap: balance;
}
.note-list a.title:hover { color: var(--accent); }
.note-list .dek {
  font-size: 0.95em;
  color: var(--muted);
  margin-top: 0.5rem;
  line-height: 1.5;
  max-width: 56ch;
}
.note-list .meta {
  font-family: var(--mono);
  font-size: 0.75rem;
  color: var(--faint);
  margin-top: 0.55rem;
  letter-spacing: 0.04em;
}

header.primer {
  padding: clamp(1.75rem, 4vw, 3.25rem) 0 1.35rem;
  width: min(var(--prose), 100%);
  margin-inline: auto;
}
header.primer h1 {
  font-family: var(--display);
  font-weight: 400;
  font-size: clamp(2.15rem, 1.2rem + 3.2vw, 4.4rem);
  letter-spacing: -0.03em;
  line-height: 1.08;
  color: var(--ink);
  text-wrap: balance;
  max-width: none;
  font-synthesis: none;
}
header.primer .lead {
  font-size: clamp(1.02rem, 0.94rem + 0.28vw, 1.22rem);
  color: var(--muted);
  line-height: 1.5;
  max-width: none;
  margin-top: 1rem;
}

.byline {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem 1.25rem;
  margin-top: 1.35rem;
  padding-top: 0.9rem;
  border-top: 1px solid var(--line);
  font-family: var(--mono);
  font-size: 0.75rem;
  letter-spacing: 0.03em;
}
.byline-name { color: var(--ink); }
.byline-detail { color: var(--muted); }

.tags { display: flex; flex-wrap: wrap; gap: 0.4rem; margin-top: 1.1rem; }
.tag {
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.03em;
  border: 1px solid var(--line);
  color: var(--muted);
  padding: 0.32rem 0.55rem;
  border-radius: 0;
}

article.primer {
  width: min(var(--prose), 100%);
  margin-inline: auto;
  padding-bottom: 4rem;
}

article.primer h2 {
  font-family: var(--sans);
  font-weight: 600;
  font-size: clamp(1.2rem, 1.02rem + 0.7vw, 1.65rem);
  letter-spacing: -0.022em;
  line-height: 1.25;
  color: var(--ink);
  margin: 2.6em 0 0.7em;
  text-wrap: balance;
  font-variation-settings: "opsz" 28;
}
article.primer h2:first-child { margin-top: 1.75rem; }
article.primer h3 {
  font-family: var(--sans);
  font-weight: 600;
  font-size: 1.05em;
  letter-spacing: -0.015em;
  color: var(--ink);
  margin: 1.6em 0 0.55em;
}
article.primer p {
  color: var(--body);
  margin-bottom: var(--space);
  text-wrap: pretty;
}
article.primer em { font-style: italic; color: var(--ink); }
article.primer strong { font-weight: 600; color: var(--ink); }
article.primer ul,
article.primer ol {
  margin: 0 0 var(--space) 1.2em;
  color: var(--body);
}
article.primer li { margin-bottom: 0.4em; }

@media (max-width: 719px) {
  article.primer p,
  article.primer li {
    hyphens: auto;
    -webkit-hyphens: auto;
  }
}

article.primer blockquote {
  border-left: 2px solid var(--ink);
  padding: 0.1rem 0 0.1rem 1.1rem;
  margin: 0 0 var(--space);
}
article.primer blockquote p {
  font-family: var(--sans);
  font-style: italic;
  font-size: 1.02em;
  line-height: 1.5;
  color: var(--ink);
  margin-bottom: 0.4rem;
  max-width: none;
}
article.primer blockquote p:last-child { margin-bottom: 0; }

article.primer pre,
article.primer code { font-family: var(--mono); }
article.primer code {
  font-size: 0.88em;
  background: var(--paper);
  padding: 0.12em 0.32em;
  border-radius: 2px;
}
article.primer pre {
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 1rem 1.1rem;
  overflow-x: auto;
  font-size: 0.82rem;
  line-height: 1.55;
  margin: 0 0 var(--space);
}
article.primer pre code { background: none; padding: 0; }

article.primer figure {
  margin: 1.75rem 0 2rem;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 0;
  overflow: hidden;
  width: 100%;
}
article.primer figcaption {
  padding: 0.7rem 1rem 0.85rem;
  font-family: var(--mono);
  font-size: 0.75rem;
  color: var(--muted);
  line-height: 1.5;
  border-top: 1px solid var(--line);
}

.canvas-wrap {
  position: relative;
  width: 100%;
  background: var(--paper);
}
.canvas-wrap canvas {
  display: block;
  width: 100%;
  height: auto;
}
.mode-row {
  display: flex;
  gap: 0;
  padding: 0;
  border-bottom: 1px solid var(--line);
  flex-wrap: wrap;
  background: var(--paper);
}
.mode-row::before {
  content: "Try";
  font-family: var(--mono);
  font-size: 0.68rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--faint);
  align-self: center;
  padding: 0 0.8rem;
}
.mbtn {
  min-height: 2.75rem;
  padding: 0.4rem 0.9rem;
  border-radius: 0;
  font-family: var(--mono);
  font-size: 0.74rem;
  letter-spacing: 0.01em;
  border: none;
  border-right: 1px solid var(--line);
  color: var(--muted);
  cursor: pointer;
  background: transparent;
}
.mbtn:hover { color: var(--ink); background: color-mix(in srgb, var(--paper) 70%, #fff); }
.mbtn.active,
.mbtn[aria-checked="true"] {
  color: var(--ink);
  background: #fff;
  box-shadow: inset 0 -2px 0 var(--accent);
  font-weight: 500;
}

.table-wrap {
  overflow-x: auto;
  margin: 0 0 var(--space);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  width: 100%;
}
article.primer table {
  width: 100%;
  border-collapse: collapse;
  font-family: var(--mono);
  font-size: 0.78rem;
  margin: 0;
  font-variant-numeric: tabular-nums;
}
article.primer th,
article.primer td {
  text-align: left;
  padding: 0.65rem 0.8rem;
  border-bottom: 1px solid var(--line);
  color: var(--body);
  vertical-align: top;
}
article.primer tr:last-child td { border-bottom: none; }
article.primer th {
  font-size: 0.68rem;
  letter-spacing: 0.07em;
  text-transform: uppercase;
  color: var(--muted);
  font-weight: 500;
  background: var(--paper);
}

article.primer .footnotes,
article.primer > .footnote {
  margin-top: 3rem;
  padding-top: 1.35rem;
  border-top: 1px solid var(--line);
  font-family: var(--sans);
  font-size: 0.9em;
}
article.primer .footnotes ol,
article.primer > .footnote ol { padding-left: 1.2rem; }
article.primer .footnotes li,
article.primer > .footnote li { color: var(--muted); line-height: 1.5; margin-bottom: 0.4rem; }
article.primer sup,
article.primer a.footnote-ref {
  font-family: var(--mono);
  font-size: 0.68em;
  font-weight: 500;
  color: var(--accent);
  text-decoration: none;
  cursor: help;
}

.fn-pop {
  position: fixed;
  z-index: 80;
  width: min(18.5rem, calc(100vw - 2rem));
  max-height: min(42vh, 22rem);
  overflow: auto;
  background: var(--paper);
  border: 1px solid var(--line);
  border-left: 2px solid var(--accent);
  padding: 0.75rem 0.9rem;
  font-family: var(--sans);
  font-size: 0.84rem;
  line-height: 1.5;
  color: var(--body);
  pointer-events: none;
  opacity: 0;
}
.fn-pop.on {
  opacity: 1;
  pointer-events: auto;
}
.fn-pop[hidden] { display: none; }
.fn-pop.on[hidden] { display: block; }
.fn-pop p { margin: 0 0 0.4rem; max-width: none; }
.fn-pop p:last-child { margin-bottom: 0; }

.tldr {
  border: 1px solid var(--line);
  background: var(--paper);
  padding: 1rem 1.15rem 1.05rem;
  margin: 0 0 2.1rem;
}
.tldr > p:first-child {
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent);
  font-weight: 500;
  margin-bottom: 0.7rem;
}
article.primer .tldr ul {
  margin: 0 0 0 1.1rem;
  max-width: none;
}
article.primer .tldr li {
  color: var(--ink);
  margin-bottom: 0.55rem;
  line-height: 1.5;
}
article.primer .tldr li:last-child { margin-bottom: 0; }

.aside {
  font-family: var(--mono);
  font-size: 0.84rem;
  color: var(--ink);
  background: var(--paper);
  border: 1px solid var(--line);
  border-left: 2px solid var(--accent);
  padding: 0.9rem 1rem;
  margin: 0 0 var(--space);
  line-height: 1.55;
  border-radius: 0;
}
.aside strong { color: var(--ink); font-weight: 500; }

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}

footer.site {
  padding: 2.5rem 0 max(3.25rem, env(safe-area-inset-bottom, 0px));
  border-top: 1px solid var(--line);
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--muted);
}

.glossary-scrim {
  position: fixed;
  inset: 0;
  z-index: 125;
  background: rgb(22 21 19 / 0.28);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s ease;
}
.glossary-scrim.on {
  opacity: 1;
  pointer-events: auto;
}

.glossary {
  position: fixed;
  top: 0;
  right: 0;
  width: min(24rem, 92vw);
  height: 100vh;
  height: 100dvh;
  background: var(--bg);
  border-left: 1px solid var(--line);
  overflow-y: auto;
  z-index: 130;
  transform: translateX(100%);
  transition: transform 0.2s ease;
}
.glossary.open { transform: translateX(0); }
.glossary-toggle {
  position: static;
  writing-mode: horizontal-tb;
  transform: none;
  min-height: 2.5rem;
  padding: 0;
  border: none;
  background: none;
  cursor: pointer;
  font-family: var(--mono);
  font-size: 0.78rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--muted);
}
.glossary-toggle:hover,
.glossary-toggle[aria-expanded="true"] {
  color: var(--ink);
}
.glossary-head {
  position: sticky;
  top: 0;
  padding: 1rem 1rem 0.75rem;
  border-bottom: 1px solid var(--line);
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted);
  background: var(--bg);
}
.glossary-close {
  background: none;
  border: none;
  min-width: 2.75rem;
  min-height: 2.75rem;
  font-size: 1.3rem;
  color: var(--muted);
  cursor: pointer;
  font-family: var(--sans);
}
.gl-item { border-bottom: 1px solid var(--line); }
.gl-term {
  display: block;
  width: 100%;
  text-align: left;
  background: none;
  border: none;
  min-height: 2.75rem;
  padding: 0.75rem 1rem;
  font-family: var(--sans);
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--ink);
  cursor: pointer;
}
.gl-def {
  display: none;
  padding: 0 1rem 1rem;
  font-size: 0.9rem;
  color: var(--muted);
  line-height: 1.5;
}
.gl-item.expanded .gl-def { display: block; }

@media (max-width: 719px) {
  .mode-row::before { display: none; }
  .toc a { min-height: 2.75rem; }
}

/* Same-width center column. TOC sits in the left margin so the page stays even. */
@media (min-width: 1100px) {
  html { scroll-padding-top: 1.5rem; }

  body.primer-page main {
    display: grid;
    grid-template-columns: minmax(0, 1fr) minmax(0, var(--prose)) minmax(0, 1fr);
    column-gap: clamp(1.25rem, 2.4vw, 2.75rem);
    align-items: start;
  }
  body.primer-page header.primer {
    grid-column: 2;
    grid-row: 1;
    width: auto;
    margin-inline: 0;
  }
  body.primer-page article.primer {
    grid-column: 2;
    grid-row: 2;
    width: auto;
    margin-inline: 0;
  }
  body.primer-page .toc {
    grid-column: 1;
    grid-row: 2;
    justify-self: end;
    width: min(13.5rem, 100%);
    position: sticky;
    top: 1.25rem;
    align-self: start;
    margin: 0;
    padding: 0;
    background: transparent;
    backdrop-filter: none;
    border-bottom: none;
    max-height: calc(100dvh - 2.5rem);
    overflow-y: auto;
  }
  body.primer-page .toc.is-stuck { border-bottom: none; }
  body.primer-page .toc-list {
    flex-direction: column;
    gap: 0;
    overflow: visible;
    counter-reset: sec;
  }
  body.primer-page .toc a {
    display: block;
    white-space: normal;
    min-height: 0;
    padding: 0.42rem 0 0.42rem 0.7rem;
    border-bottom: none;
    border-left: 2px solid transparent;
    line-height: 1.35;
    font-size: 0.74rem;
  }
  body.primer-page .toc a:hover,
  body.primer-page .toc a[aria-current="true"] {
    border-bottom: none;
    border-left-color: var(--accent);
    color: var(--ink);
  }
}

@media (min-width: 1400px) {
  body.primer-page .toc { width: min(15rem, 100%); }
}