:root {
  --bg: #fbfaf6;
  --paper: #fffefb;
  --ink: #142b29;
  --ink-soft: #3d504d;
  --faint: #5d6b68;
  --line: #d6ddd8;
  --line-soft: #e7ebe7;
  --accent: #0b6f6a;
  --accent-dark: #074e4b;
  --accent-soft: #e4f1ed;
  --quote: #a34f31;
  --surface: #f2f3ee;
  --warm: #f4ead8;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
  --serif: "Iowan Old Style", "Palatino Linotype", "Book Antiqua", Charter, Georgia, serif;
  --mono: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  --measure: 44rem;
  --wide: 70rem;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  color: var(--ink);
  background: var(--bg);
  font-family: var(--serif);
  font-size: 1.075rem;
  line-height: 1.72;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

a { color: var(--accent); text-decoration-thickness: .08em; text-underline-offset: .16em; }
img { display: block; max-width: 100%; height: auto; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; }
::selection { color: var(--ink); background: #cfe5df; }

.skip-link {
  position: fixed;
  top: .75rem;
  left: .75rem;
  z-index: 100;
  padding: .65rem .9rem;
  color: #fff;
  background: var(--accent-dark);
  border-radius: 4px;
  font-family: var(--sans);
  font-size: .82rem;
  font-weight: 700;
  text-decoration: none;
  transform: translateY(-200%);
}
.skip-link:focus { transform: translateY(0); }

/* Masthead */
.masthead {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(251, 250, 246, .92);
  border-bottom: 1px solid var(--line-soft);
  backdrop-filter: blur(8px);
}
.masthead-inner {
  width: min(var(--wide), calc(100% - 2.5rem));
  min-height: 3.75rem;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  font-family: var(--sans);
}
.masthead-title {
  color: var(--ink);
  font-size: .76rem;
  font-weight: 760;
  letter-spacing: .13em;
  text-transform: uppercase;
  text-decoration: none;
}
.masthead nav { display: flex; align-items: center; gap: 1.1rem; font-size: .78rem; font-weight: 650; }
.masthead nav a {
  min-height: 2.75rem;
  display: inline-flex;
  align-items: center;
  color: var(--ink-soft);
  text-decoration: none;
}
.masthead nav a:hover { color: var(--accent); }

/* Hero */
.hero {
  width: min(var(--measure), calc(100% - 2.5rem));
  margin: 0 auto;
  padding: 5rem 0 3.25rem;
  text-align: left;
}
.hero h1 {
  margin: 0 0 1.25rem;
  font-family: var(--serif);
  font-size: clamp(2.1rem, 4vw, 2.85rem);
  font-weight: 700;
  line-height: 1.12;
  letter-spacing: -.03em;
  text-wrap: balance;
}
.hero-note {
  max-width: 52rem;
  margin: 0 0 1rem;
  color: var(--ink-soft);
  font-size: clamp(1.08rem, 2.1vw, 1.28rem);
  line-height: 1.52;
}
.hero-byline {
  margin: 0 0 1.5rem;
  color: var(--faint);
  font-family: var(--sans);
  font-size: .8rem;
  font-weight: 560;
}
.hero-links {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-start;
  gap: .65rem;
  font-family: var(--sans);
}
.hero-links a {
  min-height: 2.75rem;
  display: inline-flex;
  align-items: center;
  padding: .65rem 1rem;
  border-radius: 4px;
  font-size: .82rem;
  font-weight: 700;
  text-decoration: none;
}
.hero-cta {
  color: #fff;
  background: var(--accent);
  border: 1px solid var(--accent);
}
.hero-cta:hover { color: #fff; background: var(--accent-dark); border-color: var(--accent-dark); }
.hero-secondary {
  color: var(--ink);
  background: transparent;
  border: 1px solid var(--line);
}
.hero-secondary:hover { color: var(--accent-dark); border-color: #9abdb6; background: var(--accent-soft); }
.hero-cta-note {
  margin: .85rem 0 0;
  color: var(--faint);
  font-family: var(--sans);
  font-size: .75rem;
}

/* Contents — collapsed by default so the teaser hits the first viewport */
.contents {
  width: min(var(--measure), calc(100% - 2.5rem));
  margin: 0 auto 2.25rem;
  padding: .25rem 0;
  background: transparent;
  border-block: 1px solid var(--line);
  font-family: var(--sans);
}
.contents summary {
  min-height: 2.75rem;
  display: flex;
  align-items: center;
  cursor: pointer;
  color: var(--ink-soft);
  font-size: .74rem;
  font-weight: 750;
  letter-spacing: .11em;
  text-transform: uppercase;
  list-style: none;
}
.contents summary::-webkit-details-marker { display: none; }
.contents summary::after {
  margin-left: auto;
  content: "+";
  font-weight: 500;
}
.contents[open] summary::after { content: " −"; }
.contents nav { margin: 0 0 .8rem; }
.contents ol {
  margin: 0;
  padding: 0;
  list-style: none;
  columns: 2;
  column-gap: 1.75rem;
  font-size: .8rem;
  line-height: 1.75;
}
.contents a { color: var(--ink-soft); text-decoration-color: transparent; }
.contents a:hover { color: var(--accent); }

/* Mid-article Colab checkpoint */
.checkpoint {
  margin: 2rem 0;
  padding: 1.2rem 1.3rem;
  background: var(--warm);
  border: 1px solid #dfcfb0;
  border-radius: 8px;
  font-family: var(--sans);
}
.checkpoint p { margin: 0 0 .65rem; font-size: .95rem; line-height: 1.55; }
.checkpoint p:last-child { margin: 0; }
.checkpoint-cta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: .45rem;
  color: var(--faint);
  font-size: .78rem;
}
.checkpoint-cta a {
  display: inline-block;
  padding: .45rem .95rem;
  color: #fff;
  background: var(--accent);
  border-radius: 4px;
  font-weight: 600;
  text-decoration: none;
}
.checkpoint-cta a:hover { background: var(--accent-dark); }

/* Article */
.article {
  width: min(var(--measure), calc(100% - 2.5rem));
  margin: 0 auto;
  padding-bottom: 3rem;
}
.article > p,
.article > ul,
.article > ol,
.article > blockquote,
.article > pre,
.article > details,
.article > .table-wrap,
.article > .checkpoint { margin: 0 0 1.2rem; }
.article ul, .article ol { padding-left: 1.3rem; }
.article li { margin-bottom: .4rem; }
.article .standfirst {
  margin-bottom: 1.5rem;
  color: var(--ink);
  font-size: clamp(1.2rem, 2.3vw, 1.38rem);
  font-weight: 530;
  line-height: 1.5;
  letter-spacing: -.01em;
}
.article details {
  padding: .85rem 1rem;
  background: var(--surface);
  border: 1px solid var(--line-soft);
  border-radius: 10px;
  font-family: var(--sans);
  font-size: .9rem;
}
.article details summary {
  cursor: pointer;
  color: var(--ink-soft);
  font-weight: 600;
}
.article details[open] summary { margin-bottom: .75rem; }

h2, h3 {
  letter-spacing: -.015em;
  line-height: 1.25;
  scroll-margin-top: 4.5rem;
  text-wrap: balance;
}
h2 {
  margin: 3.75rem 0 1.1rem;
  padding-top: 1.8rem;
  border-top: 1px solid var(--line-soft);
  font-family: var(--serif);
  font-size: clamp(1.72rem, 3.2vw, 2.15rem);
  font-weight: 700;
  letter-spacing: -.025em;
}
.article > h2:first-child { margin-top: 0; padding-top: 0; border-top: 0; }
h3 {
  margin: 2.25rem 0 .8rem;
  font-family: var(--serif);
  font-size: 1.08rem;
  font-weight: 700;
}

blockquote {
  margin: 1.6rem 0;
  padding: 1rem 1.2rem;
  background: #f7f0e5;
  border-left: 3px solid var(--quote);
  border-radius: 0 6px 6px 0;
}
blockquote p { margin: 0 0 .5rem; }
blockquote p:last-child { margin: 0; }
blockquote strong { color: var(--ink); font-weight: 650; }

.article > p strong { font-weight: 650; color: var(--ink); }

/* Figures */
.figure {
  width: min(var(--wide), calc(100vw - 2.5rem));
  margin: 2.5rem 0;
  margin-left: 50%;
  transform: translateX(-50%);
  text-align: center;
}
.figure-wide {
  width: min(var(--wide), calc(100vw - 2.5rem));
}
.figure.figure-wide img {
  width: 100%;
  max-height: none;
}
.figure img {
  margin: 0 auto;
  max-height: 70vh;
  background: var(--paper);
  border: 1px solid var(--line-soft);
  border-radius: 8px;
  box-shadow: 0 14px 34px rgba(20, 43, 41, .07);
}
.figure figcaption {
  max-width: var(--measure);
  margin: .85rem auto 0;
  color: var(--faint);
  font-family: var(--sans);
  font-size: .84rem;
  line-height: 1.55;
}
.figure figcaption b,
.figure figcaption strong { color: var(--ink-soft); font-weight: 620; }
.motion-fallback { display: none; }
.figure pre.mermaid {
  margin: 0;
  padding: 1.25rem;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 10px;
  text-align: center;
  overflow-x: auto;
}

/* Math */
.math-display {
  margin: 1.5rem 0;
  padding: .35rem 0;
  overflow-x: auto;
  overflow-y: hidden;
}
.katex { font-size: 1.02em; }
.katex-display { margin: 0; }

/* Tables */
table {
  width: 100%;
  margin: 1.5rem 0;
  border-collapse: collapse;
  font-family: var(--sans);
  font-size: .84rem;
  line-height: 1.5;
}
caption {
  padding: 0 0 .7rem;
  color: var(--ink-soft);
  font-size: .78rem;
  font-weight: 680;
  line-height: 1.45;
  text-align: left;
}
th, td {
  padding: .6rem .7rem;
  border-bottom: 1px solid var(--line);
  text-align: left;
  vertical-align: top;
}
thead th {
  border-bottom: 1.5px solid var(--ink);
  color: var(--ink);
  font-size: .72rem;
  font-weight: 650;
  letter-spacing: .04em;
  text-transform: uppercase;
}
tbody tr:last-child td {
  background: var(--accent-soft);
  border-bottom: 1px solid #b7d2cb;
}

/* Code */
pre {
  margin: 1.4rem 0;
  padding: 1rem 1.1rem;
  overflow-x: auto;
  background: var(--surface);
  border: 1px solid var(--line-soft);
  border-radius: 10px;
  font-family: var(--mono);
  font-size: .8rem;
  line-height: 1.6;
}
code { font-family: var(--mono); font-size: .88em; }
:not(pre) > code {
  padding: .12em .35em;
  background: var(--surface);
  border: 1px solid var(--line-soft);
  border-radius: 4px;
}

/* Footer */
.site-footer {
  width: min(var(--wide), calc(100% - 2.5rem));
  margin: 0 auto 4rem;
  font-family: var(--sans);
}
.demo-video {
  padding: clamp(1.5rem, 5vw, 3.5rem);
  color: var(--paper);
  background: var(--ink);
  border-radius: 10px;
}
.demo-video-copy {
  width: min(700px, 100%);
  margin: 0;
  text-align: left;
}
.demo-video-kicker {
  margin: 0 0 .35rem;
  color: #8bc4bb;
  font-size: .7rem;
  font-weight: 700;
  letter-spacing: .11em;
  text-transform: uppercase;
}
.demo-video h2 {
  margin: 0 0 .55rem;
  padding: 0;
  border: 0;
  color: var(--paper);
  font-size: clamp(1.65rem, 4vw, 2.5rem);
}
.demo-video-copy > p:last-child {
  margin-bottom: 0;
}
.demo-video-copy > #demo-video-description {
  max-width: 38rem;
  margin: 0 0 1.25rem;
  color: #c8d2cf;
  font-size: .95rem;
  line-height: 1.6;
}
.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: .65rem;
}
.footer-links a {
  min-height: 2.75rem;
  display: inline-flex;
  align-items: center;
  padding: .65rem 1rem;
  border-radius: 4px;
  font-size: .82rem;
  font-weight: 720;
  text-decoration: none;
}
.footer-links .hero-cta {
  color: var(--ink);
  background: #8bc4bb;
  border-color: #8bc4bb;
}
.footer-links .hero-cta:hover {
  color: var(--ink);
  background: #a8d6cf;
  border-color: #a8d6cf;
}
.footer-links .hero-secondary {
  color: var(--paper);
  border-color: #59706c;
}
.footer-links .hero-secondary:hover {
  color: var(--paper);
  background: #28423f;
  border-color: #78908c;
}
.demo-video-status {
  display: flex;
  align-items: center;
  gap: .45rem;
  margin: 1.25rem 0 0;
  color: #93a39f;
  font-size: .72rem;
}
.demo-video-status span {
  width: .42rem;
  height: .42rem;
  background: #8bc4bb;
  border-radius: 50%;
}

@media (max-width: 760px) {
  body { font-size: 1.02rem; }
  .masthead-inner { width: min(100% - 1.5rem, var(--wide)); }
  .masthead nav { gap: .7rem; font-size: .72rem; }
  .masthead nav a { min-height: 2.75rem; }
  .hero {
    padding: 3.25rem 0 2.5rem;
  }
  .hero h1 { font-size: clamp(1.85rem, 7.2vw, 2.3rem); line-height: 1.06; }
  .hero-note { font-size: 1.05rem; }
  .hero-links { display: grid; }
  .hero-links a { justify-content: center; }
  .contents ol { columns: 1; }
  .figure {
    width: calc(100vw - 1rem);
    overflow-x: auto;
    overscroll-behavior-inline: contain;
    -webkit-overflow-scrolling: touch;
  }
  .figure-wide img {
    width: max(52rem, 100%);
    max-width: none;
    max-height: none;
  }
  .figure figcaption {
    position: sticky;
    left: 0;
    width: calc(100vw - 2rem);
    margin-left: .5rem;
    text-align: left;
  }
  .demo-video { padding: 1rem; }
  .demo-video-copy { text-align: left; }
  h2 { margin-top: 2.5rem; font-size: 1.35rem; }
  .article > table {
    display: block;
    width: 100%;
    max-width: 100%;
    overflow-x: auto;
    overscroll-behavior-inline: contain;
    -webkit-overflow-scrolling: touch;
  }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .figure-animated img { display: none; }
  .figure-animated .motion-fallback {
    min-height: 18rem;
    display: grid;
    place-content: center;
    gap: .45rem;
    padding: 2rem;
    color: var(--ink-soft);
    background: var(--surface);
    border: 1px solid var(--line);
    border-radius: 8px;
    font-family: var(--sans);
    text-align: center;
  }
  .motion-fallback span { color: var(--faint); font-size: .82rem; }
}

/* Android prototype screenshots */
.android-demo {
  width: min(34rem, calc(100vw - 2.5rem));
  margin: 2rem 0 2.75rem;
  margin-left: 50%;
  transform: translateX(-50%);
}
.android-demo video {
  width: 100%;
  height: auto;
  display: block;
  border: 1px solid var(--line-soft);
  border-radius: 10px;
  background: #0d1014;
}
.android-demo figcaption {
  margin: .85rem .25rem .2rem;
  color: var(--faint);
  font-family: var(--sans);
  font-size: .8rem;
  line-height: 1.55;
}
.android-demo figcaption strong {
  color: var(--ink-soft);
  font-weight: 650;
}
.android-screenshot {
  margin: 0;
  padding: .65rem;
  background: var(--paper);
  border: 1px solid var(--line-soft);
  border-radius: 12px;
  box-shadow: 0 14px 34px rgba(20, 43, 41, .07);
}
.android-screenshot img {
  width: 100%;
  border: 1px solid var(--line-soft);
  border-radius: 8px;
}
.android-screenshot figcaption {
  margin: .75rem .25rem .2rem;
  color: var(--faint);
  font-family: var(--sans);
  font-size: .8rem;
  line-height: 1.5;
}
.android-screenshot figcaption strong {
  color: var(--ink-soft);
  font-weight: 650;
}