/* Verrier Labs design system tokens (Paper / Night) and shared page styles. */
  :root {
    --ground: #f4f3ef; --surface: #ffffff; --surface-sunk: #e8e6e0;
    --ink: #111111; --ink-muted: #55534e; --ink-faint: #8b8880;
    --rule: #d4d1c9; --rule-strong: var(--ink);
    --inverse: var(--ink); --on-inverse: var(--ground);
    --signal: #c8211a; --on-signal: #ffffff; --focus: #1f4fbf;

    --font-sans: "Hanken Grotesk", "Helvetica Neue", Helvetica, Arial, sans-serif;
    --font-mono: "JetBrains Mono", "SF Mono", Menlo, Consolas, monospace;

    --space-1: 4px; --space-2: 8px; --space-3: 12px; --space-4: 16px; --space-6: 24px;
    --space-8: 32px; --space-12: 48px; --space-16: 64px; --space-24: 96px; --space-32: 128px;
    --stroke-hairline: 1px; --stroke-rule: 2px; --stroke-bar: 6px;
    --radius-sm: 2px;

    --cols: 12; --gutter: 24px; --margin: 48px; --page-max: 1440px; --measure: 68ch;
    color-scheme: light;
  }
  @media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) {
      --ground: #0e0e0d; --surface: #171716; --surface-sunk: #22211f;
      --ink: #f2f1ec; --ink-muted: #a9a69e; --ink-faint: #76736c;
      --rule: #34332f; --signal: #ff5a4a; --on-signal: #0e0e0d; --focus: #7ea2ff;
      color-scheme: dark;
    }
  }
  :root[data-theme="dark"] {
    --ground: #0e0e0d; --surface: #171716; --surface-sunk: #22211f;
    --ink: #f2f1ec; --ink-muted: #a9a69e; --ink-faint: #76736c;
    --rule: #34332f; --signal: #ff5a4a; --on-signal: #0e0e0d; --focus: #7ea2ff;
    color-scheme: dark;
  }
  @media (max-width: 1023px) { :root { --cols: 8; --margin: 32px; } }
  @media (max-width: 767px)  { :root { --cols: 4; --margin: 16px; } }

  *, *::before, *::after { box-sizing: border-box; }
  html { -webkit-text-size-adjust: 100%; }
  body {
    margin: 0; background: var(--ground); color: var(--ink);
    font: 400 16px/1.5 var(--font-sans); -webkit-font-smoothing: antialiased;
    text-rendering: optimizeLegibility; overflow-x: hidden;
  }
  a { color: inherit; text-decoration: underline; text-underline-offset: 0.18em; text-decoration-thickness: 1px; transition: color 120ms linear; }
  a:hover { color: var(--signal); }
  :focus-visible { outline: 2px solid var(--focus); outline-offset: 2px; border-radius: var(--radius-sm); }
  ::selection { background: var(--ink); color: var(--ground); }

  .skip { position: absolute; left: var(--margin); top: -100px; background: #f2f1ec; color: #0e0e0d; padding: var(--space-3) var(--space-4); font-weight: 600; text-decoration: none; z-index: 10; }
  .skip:focus { top: var(--space-2); }

  /* Grid */
  .wrap { max-width: var(--page-max); margin: 0 auto; padding: 0 var(--margin); }
  .grid { display: grid; grid-template-columns: repeat(var(--cols), minmax(0, 1fr)); column-gap: var(--gutter); }

  /* Type styles */
  .label { font: 700 11px/1.2 var(--font-sans); letter-spacing: 0.08em; text-transform: uppercase; }
  .display { text-wrap: balance; font-size: clamp(40px, 3.9vw, 58px); line-height: 1.02; font-weight: 700; letter-spacing: -0.03em; margin: 0; max-width: 16em; }
  .headline { font-size: 44px; line-height: 1; font-weight: 600; letter-spacing: -0.025em; margin: 0; }
  .lead { font-size: 21px; line-height: 1.4; letter-spacing: -0.005em; margin: 0; }
  .small { font-size: 13px; line-height: 1.45; }
  .muted { color: var(--ink-muted); }
  .mono { font-family: var(--font-mono); font-variant-numeric: tabular-nums; }

  /* Logo */
  .logo { display: inline-flex; align-items: center; gap: calc(var(--logo-size) * 0.35); color: inherit; text-decoration: none; line-height: 1; --logo-size: 32px; }
  .logo:hover { color: inherit; }
  .logo-word { font-weight: 700; font-size: calc(var(--logo-size) * 0.6); letter-spacing: -0.025em; white-space: nowrap; }
  .mark { display: block; flex: none; }
  .mark-field { fill: var(--inverse); }
  .mark-line { fill: none; stroke: var(--on-inverse); stroke-width: 4; stroke-linejoin: miter; }
  .mark-planet { fill: var(--signal); }
  .mark-bare .mark-line { stroke: currentColor; }
  /* Brand mark with fixed colours (ink field, paper line, red planet) in every theme. */
  .mark-fixed .mark-field { fill: #111111; }
  .mark-fixed .mark-line { stroke: #f4f3ef; }
  .mark-fixed .mark-planet { fill: #c8211a; }

  .site-header { padding: var(--space-6) 0; }
  .site-header .wrap { display: flex; align-items: center; justify-content: space-between; gap: var(--space-6); }
  .nav { display: flex; gap: var(--space-6); }
  .nav a { text-decoration: none; padding-bottom: 2px; border-bottom: var(--stroke-rule) solid transparent; transition: color 120ms linear, border-color 120ms linear; }
  .nav a:hover { color: var(--ink); border-bottom-color: var(--signal); }
  .nav { align-items: center; }
  .x-logo { display: block; flex: none; }
  .footer-x a { display: inline-flex; align-items: center; gap: var(--space-2); }

  .actions { display: flex; flex-wrap: wrap; align-items: center; gap: var(--space-8); margin-top: var(--space-12); }


  /* Buttons */
  .btn { display: inline-flex; align-items: center; gap: var(--space-2); font: 600 17px/1 var(--font-sans); letter-spacing: -0.005em; text-decoration: none; transition: background-color 120ms linear, color 120ms linear, border-color 120ms linear; }
  .btn-primary { height: 56px; padding: 0 var(--space-6); background: var(--inverse); color: var(--on-inverse); border: var(--stroke-rule) solid var(--inverse); }
  .btn-primary:hover { background: var(--signal); border-color: var(--signal); color: var(--on-signal); }
  .btn-text { padding-bottom: 4px; border-bottom: var(--stroke-rule) solid var(--ink); }
  .btn-text:hover { color: var(--ink); border-color: var(--signal); }
  .btn-text .arrow { transition: transform 120ms linear; }
  .btn-text:hover .arrow { transform: translateX(4px); }

  /* Sections */
  main > section { margin-top: var(--space-24); }
  .section-head { grid-column: 1 / -1; border-top: var(--stroke-bar) solid var(--rule-strong); padding-top: var(--space-4); }
  .section-meta { display: flex; gap: var(--space-4); align-items: baseline; margin-bottom: var(--space-8); }
  .section-index { font: 400 11px/1.4 var(--font-mono); letter-spacing: 0.02em; color: var(--ink-muted); }
  .section-head .headline { max-width: 18ch; }

  .col-main { grid-column: 1 / span 7; margin-top: var(--space-12); }
  .col-main .lead { max-width: 40ch; }
  .col-side { grid-column: 9 / span 4; margin-top: var(--space-12); }


  /* Metric */
  .metric { border-top: var(--stroke-bar) solid var(--rule-strong); padding-top: var(--space-3); }
  .metric-label { margin-bottom: var(--space-8); }
  .metric-value { font: 500 40px/1 var(--font-mono); letter-spacing: -0.02em; font-variant-numeric: tabular-nums; }
  .metric-note { margin-top: var(--space-2); }


  /* Contact */
  .contact-mail { display: inline-block; margin-top: var(--space-6); font-size: 44px; line-height: 1.05; font-weight: 600; letter-spacing: -0.025em; text-decoration: none; border-bottom: var(--stroke-rule) solid currentColor; padding-bottom: 4px; overflow-wrap: anywhere; }

  /* Footer */
  .site-footer { margin-top: var(--space-24); background: var(--inverse); color: var(--on-inverse); padding: var(--space-16) 0 var(--space-12); }
  .site-footer a:hover { color: inherit; opacity: 0.75; }
  .footer-brand { grid-column: 1 / span 6; }
  .footer-brand .logo { --logo-size: 40px; }
  .footer-brand .small { margin: var(--space-6) 0 0; max-width: 36ch; }
  .footer-meta { grid-column: 9 / span 4; }
  .footer-meta p { margin: var(--space-2) 0 0; }
  .footer-base { grid-column: 1 / -1; margin-top: var(--space-16); padding-top: var(--space-4); border-top: var(--stroke-hairline) solid currentColor; display: flex; flex-wrap: wrap; justify-content: space-between; gap: var(--space-4); align-items: center; }
  .theme-toggle { display: inline-flex; border: var(--stroke-hairline) solid currentColor; }
  .theme-toggle button { font: 700 11px/1.2 var(--font-sans); letter-spacing: 0.08em; text-transform: uppercase; background: transparent; color: inherit; border: 0; padding: var(--space-2) var(--space-3); cursor: pointer; transition: background-color 120ms linear, color 120ms linear; }
  .theme-toggle button + button { border-left: var(--stroke-hairline) solid currentColor; }
  .theme-toggle button[aria-pressed="true"] { background: var(--on-inverse); color: var(--inverse); }

  /* Tablet: 8 columns */
  @media (max-width: 1023px) {
    .display { font-size: 52px; }
    .col-main, .col-side { grid-column: 1 / -1; }
    .col-side { max-width: 360px; }
    .footer-brand { grid-column: 1 / span 5; }
    .footer-meta { grid-column: 6 / span 3; }
  }
  /* Mobile: 4 columns */
  @media (max-width: 767px) {
    .site-header { padding: var(--space-4) 0; }
    .nav { gap: var(--space-4); }
    .display { font-size: 40px; }
    .actions { margin-top: var(--space-8); gap: var(--space-6); }
    .headline { font-size: 36px; }
    .contact-mail { font-size: 28px; }
    .footer-brand, .footer-meta { grid-column: 1 / -1; }
    .footer-meta { margin-top: var(--space-12); }
  }
  @media (max-width: 479px) {
    .display { font-size: 34px; }
    .nav a.optional { display: none; }
    .lead { font-size: 19px; }
  }
  /* Pages other than the home page: header on the page ground, ruled off. */
  .site-header.ruled { border-bottom: var(--stroke-hairline) solid var(--rule); }
  .nav a[aria-current="page"] { border-bottom-color: var(--signal); }

  /* Articles */
  .crumbs { grid-column: 1 / -1; margin: var(--space-12) 0 0; padding: 0; list-style: none; display: flex; flex-wrap: wrap; gap: var(--space-2); color: var(--ink-muted); }
  .crumbs li + li::before { content: "/"; margin-right: var(--space-2); color: var(--ink-muted); }
  .article-head { grid-column: 1 / span 9; margin-top: var(--space-8); }
  .article-head .label { display: block; color: var(--ink-muted); margin-bottom: var(--space-6); }
  .article-head .display { max-width: 18em; }
  .article-head .lead { margin-top: var(--space-8); max-width: 44ch; color: var(--ink-muted); }
  .byline { grid-column: 1 / -1; margin-top: var(--space-12); padding-top: var(--space-3); border-top: var(--stroke-bar) solid var(--rule-strong); display: flex; flex-wrap: wrap; gap: var(--space-2) var(--space-8); color: var(--ink-muted); }
  .byline .mono { font-size: 13px; }

  .prose { grid-column: 1 / span 7; margin-top: var(--space-12); }
  .prose > * { max-width: var(--measure); }
  .prose p, .prose li { font-size: 18px; line-height: 1.6; }
  .prose p { margin: 0 0 var(--space-6); }
  .prose ul, .prose ol { margin: 0 0 var(--space-6); padding-left: 1.2em; }
  .prose li + li { margin-top: var(--space-2); }
  .prose h2 { font-size: 30px; line-height: 1.1; font-weight: 600; letter-spacing: -0.015em; margin: var(--space-16) 0 var(--space-6); padding-top: var(--space-3); border-top: var(--stroke-rule) solid var(--rule-strong); }
  .prose h3 { font-size: 21px; line-height: 1.2; font-weight: 600; letter-spacing: -0.01em; margin: var(--space-8) 0 var(--space-3); }
  .prose strong { font-weight: 600; }
  .prose .data { font-family: var(--font-mono); font-size: 0.9em; font-variant-numeric: tabular-nums; }
  .formula { font: 400 17px/1.5 var(--font-mono); background: var(--surface-sunk); padding: var(--space-4) var(--space-6); margin: 0 0 var(--space-6); overflow-x: auto; }
  .plot { margin: var(--space-8) 0 var(--space-8); max-width: none; }
  .plot svg { display: block; width: 100%; height: auto; background: var(--surface); }
  .plot figcaption { margin-top: var(--space-3); color: var(--ink-muted); }
  .plot .axis { stroke: var(--ink-muted); stroke-width: 1; fill: none; }
  .plot .grid-line { stroke: var(--rule); stroke-width: 1; }
  .plot .model { stroke: var(--signal); stroke-width: 2.5; fill: none; }
  .plot .ref { stroke: var(--ink); stroke-width: 1; stroke-dasharray: 4 4; fill: none; }
  .plot text { fill: var(--ink-muted); font: 400 12px var(--font-mono); }
  .plot text.ink { fill: var(--ink); }
  .plot .star { fill: var(--surface-sunk); stroke: var(--ink-muted); }
  .plot .planet { fill: var(--signal); }

  .video video { display: block; width: 100%; height: auto; background: #0e0e0d; }
  .video.portrait video { max-width: 432px; }
  .prose h3 a { text-decoration: none; }
  .prose h3 a:hover { text-decoration: underline; }
  .aside { grid-column: 9 / span 4; margin-top: var(--space-12); }
  .aside-inner { position: sticky; top: var(--space-8); }
  .facts { margin: 0; }
  .facts div { border-top: var(--stroke-bar) solid var(--rule-strong); padding: var(--space-3) 0 var(--space-8); }
  .facts dt { margin-bottom: var(--space-4); }
  .facts dd { margin: 0; font: 500 28px/1.05 var(--font-mono); letter-spacing: -0.02em; font-variant-numeric: tabular-nums; }
  .facts dd .small { display: block; margin-top: var(--space-2); font: 400 13px/1.45 var(--font-sans); letter-spacing: 0; color: var(--ink-muted); }

  .sources { grid-column: 1 / span 7; margin-top: var(--space-16); padding-top: var(--space-3); border-top: var(--stroke-hairline) solid var(--rule); color: var(--ink-muted); }
  .sources ul { margin: var(--space-4) 0 0; padding-left: 1.2em; }
  .sources li + li { margin-top: var(--space-2); }

  .read-next { margin-top: var(--space-24); }
  .read-list { grid-column: 1 / -1; list-style: none; margin: var(--space-8) 0 0; padding: 0; display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: var(--space-8) var(--gutter); }
  .read-list li { border-top: var(--stroke-rule) solid var(--rule-strong); padding-top: var(--space-3); }
  .read-list a { display: block; text-decoration: none; }
  .read-list .title { display: block; font-size: 24px; line-height: 1.15; font-weight: 600; letter-spacing: -0.01em; margin-top: var(--space-3); }
  .read-list .desc { display: block; margin-top: var(--space-2); color: var(--ink-muted); max-width: 44ch; }
  .read-list a:hover .title { color: var(--signal); }

  .notfound { padding: var(--space-24) 0; }
  .notfound .col-main { margin-top: var(--space-8); }

  @media (max-width: 1023px) {
    .article-head, .prose, .aside, .sources { grid-column: 1 / -1; }
    .aside-inner { position: static; }
    .facts { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 0 var(--gutter); }
  }
  @media (max-width: 767px) {
    .prose p, .prose li { font-size: 17px; }
    .prose h2 { font-size: 26px; }
    .facts { grid-template-columns: 1fr; }
    .read-list { grid-template-columns: 1fr; }
  }

  @media (prefers-reduced-motion: reduce) {
    *, *::before, *::after { transition: none !important; }
  }