:root {
  --bg: #f5f7fa;
  --bg-elev: #ffffff;
  --ink: #0b1220;
  --muted: #5c6573;
  --line: #e2e7ee;
  --accent: #0b6cff;
  --accent-ink: #0a58d0;
  --forest: #0b6cff;
  --nav: #ffffff;
  --nav-ink: #0b1220;
  --shadow: 0 12px 40px rgba(11, 18, 32, 0.06);
  --serif: "IBM Plex Sans", "Helvetica Neue", sans-serif;
  --sans: "IBM Plex Sans", "Helvetica Neue", sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, monospace;
  --wrap: 1080px;
  --code-bg: #0b1220;
}

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

html { scroll-behavior: smooth; }

body {
  margin: 0;
  color: var(--ink);
  background: var(--bg);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.65;
}

a { color: var(--accent-ink); }
a:hover { color: var(--accent); }

img, iframe { max-width: 100%; }
img { height: auto; display: block; }

.skip-link {
  position: absolute;
  left: -999px;
  top: 0;
}
.skip-link:focus {
  left: 1rem;
  top: 1rem;
  z-index: 20;
  background: #fff;
  padding: 0.4rem 0.7rem;
}

.wrap {
  width: min(var(--wrap), calc(100% - 2.4rem));
  margin: 0 auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(255, 255, 255, 0.92);
  color: var(--nav-ink);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--line);
}

.nav-wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 64px;
  gap: 1rem;
}

.brand {
  display: flex;
  align-items: baseline;
  gap: 0.45rem;
  color: inherit;
  text-decoration: none;
}

.brand-mark {
  width: 0.7rem;
  height: 0.7rem;
  border-radius: 2px;
  background: var(--accent);
  box-shadow: 0 0 0 3px rgba(11, 108, 255, 0.2);
}

.brand-name {
  font-family: var(--serif);
  font-weight: 650;
  letter-spacing: -0.03em;
  font-size: 1.25rem;
}

.brand-ver {
  font-family: var(--mono);
  font-size: 0.72rem;
  color: #7a8494;
}

.nav-toggle {
  display: none;
  background: transparent;
  color: inherit;
  border: 1px solid var(--line);
  padding: 0.35rem 0.7rem;
  font: inherit;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 0.15rem;
}

.site-nav a,
.nav-label {
  color: #3d4756;
  text-decoration: none;
  background: none;
  border: 0;
  font: inherit;
  font-size: 0.92rem;
  padding: 0.55rem 0.7rem;
  cursor: pointer;
}

.site-nav a:hover,
.nav-label:hover { color: var(--ink); }

.nav-cta {
  margin-left: 0.4rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--ink);
}

.nav-group { position: relative; }

.nav-panel {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  min-width: 13rem;
  padding: 0.45rem;
  background: #ffffff;
  border: 1px solid var(--line);
  box-shadow: var(--shadow);
}

.nav-panel a {
  display: block;
  padding: 0.45rem 0.6rem;
}

.nav-group:hover .nav-panel,
.nav-group:focus-within .nav-panel,
.nav-group.is-open .nav-panel { display: block; }

.main { padding-bottom: 4rem; }

.hero {
  padding: 4.2rem 0 2.4rem;
}

.kicker {
  font-family: var(--mono);
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent-ink);
  margin: 0 0 0.8rem;
}

.hero h1 {
  font-family: var(--serif);
  font-size: clamp(2.4rem, 5vw, 4.2rem);
  line-height: 1.05;
  letter-spacing: -0.035em;
  margin: 0 0 1rem;
  max-width: 16ch;
}

.lede {
  max-width: 40rem;
  font-size: 1.15rem;
  color: var(--muted);
  margin: 0 0 1.6rem;
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.7rem;
  margin-bottom: 2.4rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.7rem 1rem;
  border-radius: 999px;
  text-decoration: none;
  font-weight: 550;
  border: 1px solid var(--ink);
}

.btn-primary {
  background: var(--ink);
  color: var(--bg);
}

.btn-primary:hover { background: #000; color: #fff; }

.btn-ghost {
  background: transparent;
  color: var(--ink);
}

.stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1rem;
  margin: 0 0 3rem;
}

.stat {
  padding: 1rem 0;
  border-top: 1px solid var(--line);
}

.stat b {
  display: block;
  font-family: var(--serif);
  font-size: 1.5rem;
}

.stat span {
  color: var(--muted);
  font-size: 0.92rem;
}

.media-frame {
  background: var(--nav);
  border-radius: 18px;
  overflow: hidden;
  box-shadow: var(--shadow);
  aspect-ratio: 16 / 9;
}

.media-frame iframe {
  width: 100%;
  height: 100%;
  border: 0;
}

.section {
  padding: 1.2rem 0 0.4rem;
}

.section h2 {
  font-family: var(--serif);
  font-size: 2rem;
  letter-spacing: -0.03em;
  margin: 0 0 0.4rem;
}

.section-lead {
  color: var(--muted);
  max-width: 40rem;
  margin: 0 0 1.4rem;
}

.cards {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
}

.card {
  background: var(--bg-elev);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 1.15rem 1.15rem 1.25rem;
}

.card h3 {
  font-family: var(--serif);
  font-size: 1.2rem;
  margin: 0 0 0.4rem;
}

.card p { margin: 0; color: var(--muted); }

.card a {
  display: inline-block;
  margin-top: 0.8rem;
  font-weight: 550;
  text-decoration: none;
}

.features {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.8rem;
}

.feature {
  padding: 0.9rem 0;
  border-top: 1px solid var(--line);
}

.feature strong { display: block; }
.feature span { color: var(--muted); font-size: 0.95rem; }

.carousel { margin: 0.4rem 0 1.6rem; }
.carousel-stage { position: relative; }
.carousel-slide { display: none; }
.carousel-slide.is-active { display: block; }
.carousel-slide h3 {
  font-size: 1.15rem;
  margin: 0 0 0.7rem;
}
.carousel-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.8rem;
  margin-top: 0.9rem;
}
.carousel-btn {
  width: 2.4rem;
  height: 2.4rem;
  border: 1px solid var(--line);
  background: var(--bg-elev);
  color: var(--ink);
  border-radius: 999px;
  font: inherit;
  cursor: pointer;
}
.carousel-btn:hover { border-color: var(--accent); color: var(--accent-ink); }
.carousel-dots { display: flex; gap: 0.4rem; }
.carousel-dot {
  width: 0.55rem;
  height: 0.55rem;
  padding: 0;
  border: 0;
  border-radius: 999px;
  background: #c5cdd8;
  cursor: pointer;
}
.carousel-dot.is-active { background: var(--accent); }

.doc {
  width: min(860px, calc(100% - 2.4rem));
  margin: 0 auto;
  padding-top: 2.4rem;
}

.build-path {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
  margin: 0 0 1.8rem;
}

.build-path a {
  text-decoration: none;
  color: var(--ink);
  font-size: 0.8rem;
  padding: 0.28rem 0.6rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--bg-elev);
}

.build-path a.is-active {
  background: var(--ink);
  color: var(--bg);
  border-color: var(--ink);
}

.step-next {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  margin: 2.2rem 0 2.4rem;
  padding-top: 1.4rem;
  border-top: 1px solid var(--line);
}

.step-next .btn { text-decoration: none; }
.step-next-back { min-width: 1px; }

.figure-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.7rem;
  margin: 1rem 0 1.4rem;
}

.figure-grid.one { grid-template-columns: 1fr; }

.figure {
  margin: 0;
  background: var(--bg-elev);
  border: 1px solid var(--line);
  border-radius: 12px;
  overflow: hidden;
}

.figure img { width: 100%; }
.figure figcaption {
  font-size: 0.86rem;
  color: var(--muted);
  padding: 0.55rem 0.75rem 0.7rem;
}

.callout {
  margin: 1rem 0;
  padding: 0.85rem 1rem;
  border-radius: 12px;
  background: #eef4ff;
  border: 1px solid #d5e3ff;
}

.callout.warn {
  background: #fff4f0;
  border-color: #ffd4c8;
}

.step-meta {
  font-family: var(--mono);
  font-size: 0.78rem;
  color: var(--muted);
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.toc a { text-decoration: none; }

@media (max-width: 640px) {
  .figure-grid { grid-template-columns: 1fr; }
}

.doc-hero h1 {
  font-family: var(--serif);
  font-size: clamp(2rem, 4vw, 3rem);
  letter-spacing: -0.03em;
  margin: 0 0 0.6rem;
}

.doc-hero .lead {
  color: var(--muted);
  font-size: 1.1rem;
  margin: 0 0 1.6rem;
}

.prose h1 { display: none; }
.prose h2,
.prose h3,
.prose h4 {
  font-family: var(--serif);
  letter-spacing: -0.02em;
  line-height: 1.25;
}

.prose h2 { font-size: 1.7rem; margin-top: 2.2rem; }
.prose h3 { font-size: 1.25rem; margin-top: 1.6rem; }
.prose p { margin: 0.8rem 0; }
.prose ul, .prose ol { padding-left: 1.2rem; }

.prose pre,
.prose code {
  font-family: var(--mono);
  font-size: 0.86em;
}

.prose :not(pre) > code {
  background: #0b1220;
  color: #d7e3f4;
  padding: 0.12em 0.4em;
  border-radius: 4px;
}

.code-block {
  position: relative;
  margin: 1rem 0;
  background: var(--code-bg);
  border: 1px solid #1e293b;
  border-radius: 12px;
}

.prose pre,
.prose pre[class*="language-"] {
  overflow: auto;
  background: var(--code-bg) !important;
  color: #d7e3f4;
  text-shadow: none;
  font-family: var(--mono);
  padding: 2.4rem 1.1rem 1.1rem;
  border-radius: 12px;
  margin: 0;
  box-shadow: none;
}

.prose pre code,
.prose pre code[class*="language-"] {
  background: transparent !important;
  color: inherit;
  text-shadow: none;
  font-family: var(--mono);
  padding: 0;
  font-size: inherit;
}

.copy-btn {
  position: absolute;
  top: 0.55rem;
  right: 0.55rem;
  z-index: 1;
  border: 1px solid #334155;
  background: #1e293b;
  color: #e2e8f0;
  font: inherit;
  font-size: 0.75rem;
  padding: 0.25rem 0.55rem;
  border-radius: 6px;
  cursor: pointer;
}

.copy-btn:hover,
.copy-btn.is-copied { border-color: var(--accent); color: #fff; }

.prose blockquote {
  margin: 1rem 0;
  padding: 0.2rem 0 0.2rem 1rem;
  border-left: 3px solid var(--accent);
  color: var(--muted);
}

.prose table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.92rem;
  background: var(--bg-elev);
}

.prose th,
.prose td {
  border: 1px solid var(--line);
  padding: 0.45rem 0.55rem;
  vertical-align: top;
}

.prose iframe {
  width: 100%;
  aspect-ratio: 16 / 9;
  height: auto;
  border: 0;
  border-radius: 12px;
}

.site-footer {
  border-top: 1px solid var(--line);
  padding: 2.4rem 0 2.8rem;
  background: #eef1f5;
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr 1.4fr;
  gap: 1.4rem;
}

.footer-label {
  font-family: var(--mono);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin: 0 0 0.5rem;
}

.site-footer a,
.site-footer p { display: block; margin: 0.2rem 0; }
.muted { color: var(--muted); }

.year-chart-wrap {
  position: relative;
  margin: 0.4rem 0 1.6rem;
}

.year-chart-totals {
  position: absolute;
  top: 0;
  right: 0;
  display: flex;
  gap: 0.85rem;
  z-index: 1;
  font-size: 0.78rem;
  color: var(--muted);
}

.year-chart-totals b {
  font-family: var(--mono);
  font-size: 0.92rem;
  font-weight: 550;
  color: var(--ink);
}

.cite-list { list-style: none; padding: 0; }
.cite-list li {
  display: grid;
  grid-template-columns: 2rem 1fr;
  gap: 0.6rem;
  padding: 0.7rem 0;
  border-bottom: 1px solid var(--line);
}
.cite-rank {
  font-family: var(--serif);
  font-size: 1.2rem;
  color: var(--accent-ink);
}
.cite-list a { font-weight: 550; text-decoration: none; }

.year-chart {
  display: flex;
  align-items: flex-end;
  gap: 0.55rem;
  min-height: 160px;
  padding-top: 1.8rem;
  margin: 0;
}
.bar {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: flex-end;
  gap: 0.2rem;
}
.bar-fill {
  width: 100%;
  max-width: 2.2rem;
  background: var(--accent);
  border-radius: 4px 4px 0 0;
}
.bar-n, .bar-y {
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--muted);
}

.part-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
  margin: 0.4rem 0 1.6rem;
}
.part-card {
  background: var(--bg-elev);
  border: 1px solid var(--line);
  border-radius: 14px;
  overflow: hidden;
}
.part-card h3 {
  font-family: var(--serif);
  font-size: 1.15rem;
  margin: 0.8rem 0.9rem 0.2rem;
}
.part-card p, .part-card a {
  margin: 0 0.9rem 0.85rem;
  font-size: 0.92rem;
}
.stl-stage {
  height: 220px;
  background: #111827;
}
.stl-stage canvas { display: block; width: 100%; height: 100%; }
.stl-stage.is-failed {
  display: flex;
  align-items: center;
  justify-content: center;
  color: #94a3b8;
  font-size: 0.85rem;
}

@media (max-width: 640px) {
  .part-grid { grid-template-columns: 1fr; }
}

@media (max-width: 900px) {
  .stats, .cards, .features, .video-grid, .footer-grid {
    grid-template-columns: 1fr 1fr;
  }

  .nav-toggle { display: inline-flex; }

  .site-nav {
    display: none;
    position: absolute;
    left: 0;
    right: 0;
    top: 64px;
    background: #ffffff;
    flex-direction: column;
    align-items: stretch;
    padding: 0.6rem 1.2rem 1.2rem;
  }

  .site-header.is-open .site-nav { display: flex; }

  .nav-panel {
    position: static;
    display: none;
    min-width: 0;
    box-shadow: none;
    border: 0;
    padding-left: 0.6rem;
  }

  .nav-group.is-open .nav-panel { display: block; }
}

@media (max-width: 640px) {
  .stats, .cards, .features, .video-grid, .footer-grid {
    grid-template-columns: 1fr;
  }
}