/* ─────────────────────────────────────────────────────────────────
   Rento Mucenieks · pitch page · 05-instrument-geist (UNIFIED)
   INSTRUMENT / PRECISION - Teenage Engineering × Braun × Bloomberg
   Typography: Geist (display/body) + Geist Mono (instrument chrome)
   One stylesheet. Hand-written. No build step. No scripts.

   THEME ARCHITECTURE:
   - :root holds LIGHT tokens as base (default).
   - @media prefers-color-scheme: dark overrides to DARK tokens.
   - :root:has(#theme-light:checked) forces LIGHT regardless of system.
   - :root:has(#theme-dark:checked) forces DARK regardless of system.
   - :has() rules appear after the media query so they win at equal
     specificity. If :has() is unsupported, the media query path still
     works correctly - graceful degradation guaranteed.

   THEME TOKENS (38 theme-specific tokens):
   --bg, --bg-raised, --bg-box, --bg-rule, --dot
   --ink, --ink-mid, --ink-dim, --ink-faint
   --signal, --signal-dim, --signal-wash
   --rule, --rule-mid
   --color-scheme
   --masthead-label-opacity
   --sec-no-before-opacity
   --hero-instrument-color
   --hero-gauge-bar-bg
   --d-flow-stroke
   --d-arrow-fill
   --d-sub-fill
   --d-sub-signal-fill
   --d-label-dim-fill
   --plot-dot-fill
   --plot-p-cost-fill
   --plot-axis-stroke
   --plot-frontier-opacity
   --delta-label-color
   --cta-mail-prefix-color
   --masthead-date-color
   --switcher-bg
   --switcher-bg-active
   --switcher-border
   --switcher-text
   --switcher-text-active
   --switcher-signal

   AA notes (WCAG 2.1):
   DARK: body ~14:1, signal amber oklch(76% 0.148 78) ~9.8:1 on dark bg
   LIGHT: body ~14:1, signal deep-amber oklch(44% 0.130 62) ~5.0:1 on light bg
   ───────────────────────────────────────────────────────────────── */

/* ── self-hosted fonts: Geist + Geist Mono, subset woff2, variable wght ── */
@font-face {
  font-family: 'Geist';
  src: url('fonts/geist.woff2') format('woff2');
  font-weight: 100 900;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: 'Geist Mono';
  src: url('fonts/geist-mono.woff2') format('woff2');
  font-weight: 100 900;
  font-style: normal;
  font-display: swap;
}

/* ── LIGHT theme tokens (default / base) ─────────────────────────── */
:root {
  /* base: near-white with faint warm tint - engineering paper */
  --bg:          oklch(97% 0.006 80);
  --dot:         oklch(92% 0.008 80);   /* sampling grid - whisper on paper (within ~5% L of bg) */
  --bg-raised:   oklch(94% 0.007 80);
  --bg-box:      oklch(91% 0.008 80);
  --bg-rule:     oklch(88% 0.009 80);

  /* text: cool-cast ink for contrast against warm bg */
  --ink:         oklch(18% 0.010 240);
  --ink-mid:     oklch(29% 0.010 240);
  --ink-dim:     oklch(48% 0.010 240);
  --ink-faint:   oklch(66% 0.009 240);

  /* signal: deep amber/ochre - darkened for AA on light bg
     oklch(44% 0.130 62): rel. lum ≈ 0.145 → ratio ≈ 5.02:1 on bg ✓ */
  --signal:      oklch(44% 0.130 62);
  --signal-dim:  oklch(52% 0.115 62);  /* decorative only - not for text */
  --signal-wash: oklch(93% 0.028 78);

  /* rule */
  --rule:        oklch(86% 0.008 240);
  --rule-mid:    oklch(78% 0.009 240);

  /* color-scheme for browser chrome */
  --color-scheme: light;

  /* theme-specific detail tokens */
  --masthead-label-opacity:  1;
  --sec-no-before-opacity:   0.5;
  --hero-instrument-color:   var(--signal);
  --hero-gauge-bar-bg:       var(--bg-rule);
  --d-flow-stroke:           var(--ink-dim);
  --d-arrow-fill:            var(--ink-dim);
  --d-sub-fill:              var(--ink-mid);
  --d-sub-signal-fill:       var(--signal);
  --d-label-dim-fill:        var(--ink-mid);
  --plot-dot-fill:           var(--ink-dim);
  --plot-p-cost-fill:        var(--signal);
  --plot-axis-stroke:        var(--ink-dim);
  --plot-frontier-opacity:   0.8;
  --delta-label-color:       var(--signal);
  --cta-mail-prefix-color:   var(--signal);
  --masthead-date-color:     var(--signal);

  /* theme switcher control */
  --switcher-bg:             oklch(91% 0.008 80);
  --switcher-bg-active:      oklch(97% 0.006 80);
  --switcher-border:         oklch(78% 0.009 240);
  --switcher-text:           oklch(48% 0.010 240);
  --switcher-text-active:    oklch(44% 0.130 62);
  --switcher-signal:         oklch(44% 0.130 62);

  /* type */
  --font-mono:    'Geist Mono', ui-monospace, 'SF Mono', Menlo, Consolas, monospace;
  --font-display: 'Geist', 'Helvetica Neue', Arial, sans-serif;

  /* layout */
  --wrap:   72rem;
  --pad:    clamp(1.5rem, 5vw, 3.5rem);
  --rail:   clamp(3.5rem, 1rem + 5vw, 6rem);
  --gap:    clamp(1.5rem, 3vw, 2.5rem);
  --col:    48rem;

  /* baseline unit: 6px module */
  --u: 0.375rem;

  color-scheme: light;
}

/* ── DARK theme tokens - system auto ─────────────────────────────── */
@media (prefers-color-scheme: dark) {
  :root {
    --bg:          oklch(11% 0.006 240);
    --dot:         oklch(23% 0.011 240);     /* sampling grid - whisper on instrument-black (near-black needs a larger L step) */
    --bg-raised:   oklch(14.5% 0.007 240);
    --bg-box:      oklch(18% 0.010 240);
    --bg-rule:     oklch(22% 0.008 240);

    --ink:         oklch(92% 0.006 80);
    --ink-mid:     oklch(75% 0.006 80);
    --ink-dim:     oklch(58% 0.007 80);
    --ink-faint:   oklch(44% 0.007 80);

    /* signal: warm amber - bright for dark bg
       oklch(76% 0.148 78): rel. lum ≈ 0.508 → ratio ~9.8:1 on dark bg ✓ */
    --signal:      oklch(76% 0.148 78);
    --signal-dim:  oklch(64% 0.126 78);
    --signal-wash: oklch(19% 0.038 78);

    --rule:        oklch(24% 0.008 240);
    --rule-mid:    oklch(34% 0.009 240);

    --color-scheme: dark;

    --masthead-label-opacity:  0.9;
    --sec-no-before-opacity:   0.6;
    --hero-instrument-color:   var(--signal-dim);
    --hero-gauge-bar-bg:       var(--bg-raised);
    --d-flow-stroke:           var(--ink-mid);
    --d-arrow-fill:            var(--ink-mid);
    --d-sub-fill:              var(--ink-dim);
    --d-sub-signal-fill:       var(--signal-dim);
    --d-label-dim-fill:        var(--ink-mid);
    --plot-dot-fill:           var(--ink-mid);
    --plot-p-cost-fill:        var(--signal-dim);
    --plot-axis-stroke:        var(--ink-dim);
    --plot-frontier-opacity:   0.7;
    --delta-label-color:       var(--signal-dim);
    --cta-mail-prefix-color:   var(--signal-dim);
    --masthead-date-color:     var(--signal-dim);

    --switcher-bg:             oklch(18% 0.010 240);
    --switcher-bg-active:      oklch(14.5% 0.007 240);
    --switcher-border:         oklch(34% 0.009 240);
    --switcher-text:           oklch(62% 0.007 80);
    --switcher-text-active:    oklch(76% 0.148 78);
    --switcher-signal:         oklch(76% 0.148 78);

    color-scheme: dark;
  }
}

/* ── Manual LIGHT override (:has() - wins over media query) ──────── */
:root:has(#theme-light:checked) {
  --dot:         oklch(92% 0.008 80);
  --bg:          oklch(97% 0.006 80);
  --bg-raised:   oklch(94% 0.007 80);
  --bg-box:      oklch(91% 0.008 80);
  --bg-rule:     oklch(88% 0.009 80);

  --ink:         oklch(18% 0.010 240);
  --ink-mid:     oklch(29% 0.010 240);
  --ink-dim:     oklch(48% 0.010 240);
  --ink-faint:   oklch(66% 0.009 240);

  --signal:      oklch(44% 0.130 62);
  --signal-dim:  oklch(52% 0.115 62);
  --signal-wash: oklch(93% 0.028 78);

  --rule:        oklch(86% 0.008 240);
  --rule-mid:    oklch(78% 0.009 240);

  --color-scheme: light;

  --masthead-label-opacity:  1;
  --sec-no-before-opacity:   0.5;
  --hero-instrument-color:   var(--signal);
  --hero-gauge-bar-bg:       var(--bg-rule);
  --d-flow-stroke:           var(--ink-dim);
  --d-arrow-fill:            var(--ink-dim);
  --d-sub-fill:              var(--ink-mid);
  --d-sub-signal-fill:       var(--signal);
  --d-label-dim-fill:        var(--ink-mid);
  --plot-dot-fill:           var(--ink-dim);
  --plot-p-cost-fill:        var(--signal);
  --plot-axis-stroke:        var(--ink-dim);
  --plot-frontier-opacity:   0.8;
  --delta-label-color:       var(--signal);
  --cta-mail-prefix-color:   var(--signal);
  --masthead-date-color:     var(--signal);

  --switcher-bg:             oklch(91% 0.008 80);
  --switcher-bg-active:      oklch(97% 0.006 80);
  --switcher-border:         oklch(78% 0.009 240);
  --switcher-text:           oklch(48% 0.010 240);
  --switcher-text-active:    oklch(44% 0.130 62);
  --switcher-signal:         oklch(44% 0.130 62);

  color-scheme: light;
}

/* ── Manual DARK override (:has() - wins over media query) ───────── */
:root:has(#theme-dark:checked) {
  --dot:         oklch(23% 0.011 240);
  --bg:          oklch(11% 0.006 240);
  --bg-raised:   oklch(14.5% 0.007 240);
  --bg-box:      oklch(18% 0.010 240);
  --bg-rule:     oklch(22% 0.008 240);

  --ink:         oklch(92% 0.006 80);
  --ink-mid:     oklch(75% 0.006 80);
  --ink-dim:     oklch(58% 0.007 80);
  --ink-faint:   oklch(44% 0.007 80);

  --signal:      oklch(76% 0.148 78);
  --signal-dim:  oklch(64% 0.126 78);
  --signal-wash: oklch(19% 0.038 78);

  --rule:        oklch(24% 0.008 240);
  --rule-mid:    oklch(34% 0.009 240);

  --color-scheme: dark;

  --masthead-label-opacity:  0.9;
  --sec-no-before-opacity:   0.6;
  --hero-instrument-color:   var(--signal-dim);
  --hero-gauge-bar-bg:       var(--bg-raised);
  --d-flow-stroke:           var(--ink-mid);
  --d-arrow-fill:            var(--ink-mid);
  --d-sub-fill:              var(--ink-dim);
  --d-sub-signal-fill:       var(--signal-dim);
  --d-label-dim-fill:        var(--ink-mid);
  --plot-dot-fill:           var(--ink-mid);
  --plot-p-cost-fill:        var(--signal-dim);
  --plot-axis-stroke:        var(--ink-dim);
  --plot-frontier-opacity:   0.7;
  --delta-label-color:       var(--signal-dim);
  --cta-mail-prefix-color:   var(--signal-dim);
  --masthead-date-color:     var(--signal-dim);

  --switcher-bg:             oklch(18% 0.010 240);
  --switcher-bg-active:      oklch(14.5% 0.007 240);
  --switcher-border:         oklch(34% 0.009 240);
  --switcher-text:           oklch(62% 0.007 80);
  --switcher-text-active:    oklch(76% 0.148 78);
  --switcher-signal:         oklch(76% 0.148 78);

  color-scheme: dark;
}

/* ── hex fallbacks for browsers without oklch ────────────────────── */
/* Light fallbacks (default) */
@supports not (color: oklch(50% 0 0)) {
  :root {
    --bg:          #f7f5f2;
    --bg-raised:   #eeece8;
    --bg-box:      #e5e2dd;
    --bg-rule:     #dbd8d2;
    --ink:         #1c1f24;
    --ink-mid:     #343840;
    --ink-dim:     #606570;
    --ink-faint:   #9096a0;
    --signal:      #6b4800;
    --signal-dim:  #8a6010;
    --signal-wash: #f5eed8;
    --rule:        #d4d0c8;
    --rule-mid:    #bfbab0;
    --dot:         #e9e6e0;
  }
}

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

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background-color: var(--bg);
  /* sampling grid: the faint dot-field the page is drawn on (whisper intensity).
     A second background layer on the page plane; opaque raised bands cover it. */
  background-image: radial-gradient(circle, var(--dot) 0.9px, transparent 1.1px);
  background-size: 24px 24px;
  color: var(--ink);
  font-family: var(--font-display);
  font-size: clamp(1rem, 0.94rem + 0.25vw, 1.125rem);
  line-height: 1.62;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  font-feature-settings: "kern" 1, "liga" 1;
  /* subtle theme transition - layout properties intentionally excluded */
  transition:
    background-color 0.15s ease,
    color 0.15s ease,
    border-color 0.15s ease;
}

/* disable transition under reduced-motion (prevents jarring flashes) */
@media (prefers-reduced-motion: reduce) {
  body,
  body * {
    transition: none !important;
  }
}

h1, h2, h3, p, figure, ol, ul { margin: 0; }
h1, h2, h3 { text-wrap: balance; }
p { text-wrap: pretty; }

::selection { background: var(--signal-wash); color: var(--signal); }

a { color: inherit; }

:focus-visible {
  outline: 1.5px solid var(--signal);
  outline-offset: 3px;
  border-radius: 1px;
}

.visually-hidden {
  position: absolute;
  width: 1px; height: 1px;
  padding: 0; margin: -1px;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
}

.skip {
  position: absolute;
  left: -100vw;
  font-family: var(--font-mono);
  font-size: 0.8rem;
}
.skip:focus {
  left: 1rem; top: 1rem;
  z-index: 100;
  background: var(--signal);
  color: var(--bg);
  padding: 0.5rem 1rem;
  border-radius: 2px;
  font-family: var(--font-mono);
}

/* ── theme switcher: zero-JS segmented control ────────────────────── */
/* Hidden radios - visually off-screen, still focusable.
   Placed at top of <body> before the masthead; labels are inside
   the masthead fieldset via `for` attribute association. */
.theme-radio {
  position: absolute;
  width: 1px; height: 1px;
  margin: -1px; padding: 0;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
  /* DO NOT use display:none / visibility:hidden - must remain focusable */
}

.theme-switcher {
  display: flex;
  align-items: stretch;
  gap: 0;
  border: 1px solid var(--switcher-border);
  border-radius: 2px;
  background: var(--switcher-bg);
  overflow: hidden;
  flex-shrink: 0;
  /* reset fieldset default styles */
  padding: 0;
  margin: 0;
  min-inline-size: 0;
}

.theme-option {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0.22rem 0.5rem;
  font-family: var(--font-mono);
  font-size: 0.60rem;
  letter-spacing: 0.09em;
  color: var(--switcher-text);
  cursor: pointer;
  border-right: 1px solid var(--switcher-border);
  white-space: nowrap;
  user-select: none;
  line-height: 1;
}
.theme-option:last-of-type { border-right: none; }

/* active option: signal color, lighter bg */
:root:has(#theme-auto:checked) .theme-option[for="theme-auto"],
:root:has(#theme-light:checked) .theme-option[for="theme-light"],
:root:has(#theme-dark:checked) .theme-option[for="theme-dark"] {
  color: var(--switcher-text-active);
  background: var(--switcher-bg-active);
}

/* Focus ring on label when its radio is keyboard-focused.
   Works because the radios are adjacent siblings of the fieldset
   (same parent <body>), and :has() checks anywhere in :root. */
:root:has(#theme-auto:focus-visible)  .theme-option[for="theme-auto"],
:root:has(#theme-light:focus-visible) .theme-option[for="theme-light"],
:root:has(#theme-dark:focus-visible)  .theme-option[for="theme-dark"] {
  outline: 1.5px solid var(--switcher-signal);
  outline-offset: -1px;
  border-radius: 1px;
}

/* ── tick ruler ──────────────────────────────────────────────────── */
.tick-ruler {
  width: 100%;
  height: 10px;
  overflow: hidden;
  position: relative;
}
.tick-track {
  position: absolute;
  inset: 0;
  background-image:
    repeating-linear-gradient(
      90deg,
      var(--ink-faint) 0,
      var(--ink-faint) 1px,
      transparent 1px,
      transparent 11px
    ),
    repeating-linear-gradient(
      90deg,
      var(--signal-dim) 0,
      var(--signal-dim) 1px,
      transparent 1px,
      transparent 55px
    );
  background-position: 0 bottom, 0 bottom;
  background-repeat: repeat-x;
  background-size: 100% 5px, 100% 10px;
}
.tick-track--foot {
  background-position: 0 top, 0 top;
}

/* ── masthead ────────────────────────────────────────────────────── */
.masthead {
  border-bottom: 1px solid var(--rule-mid);
  position: sticky;
  top: 0;
  z-index: 50;
  background: var(--bg);
  box-shadow: 0 1px 0 var(--rule);
}
.masthead-inner {
  max-width: var(--wrap);
  margin-inline: auto;
  padding: calc(var(--u) * 2) var(--pad);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.25rem 1.5rem;
  font-family: var(--font-mono);
  font-size: 0.715rem;
  line-height: 1.4;
}
.masthead-id { display: flex; align-items: center; gap: 0.6rem; }
.masthead-readout { display: flex; align-items: center; gap: 0.5rem; }
.masthead-label {
  font-size: 0.63rem;
  letter-spacing: 0.09em;
  color: var(--signal);
  padding: 0.15rem 0.4rem;
  border: 1px solid var(--signal-dim);
  border-radius: 1px;
  opacity: var(--masthead-label-opacity);
}
.masthead-name {
  color: var(--ink);
  font-weight: 700;
  letter-spacing: 0.01em;
}
.masthead-meta { color: var(--ink-mid); }
.masthead-sep {
  color: var(--ink-faint);
  margin: 0 0.1rem;
  font-size: 0.63rem;
}
.masthead-date {
  color: var(--masthead-date-color);
  font-size: 0.68rem;
}

/* ── section scaffold ────────────────────────────────────────────── */
.sec {
  max-width: var(--wrap);
  margin-inline: auto;
  padding-inline: var(--pad);
  margin-block: clamp(5rem, 12vh, 8rem);
  display: grid;
  grid-template-columns: var(--rail) minmax(0, 1fr);
  column-gap: var(--gap);
}

.sec-rail {
  grid-column: 1;
  grid-row: 1 / span 99;
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: calc(var(--u) * 2);
  padding-top: 0.2rem;
}

.sec-body {
  grid-column: 2;
  max-width: var(--col);
}

.sec-body p { max-width: 66ch; }
.sec-body p + p { margin-top: 1.1em; }
h2 + p { margin-top: calc(var(--u) * 4); }
h3 + p { margin-top: calc(var(--u) * 2); }

.sec-no {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  font-weight: 700;
  letter-spacing: 0.10em;
  color: var(--signal);
  padding: 0.2rem 0;
  display: flex;
  align-items: center;
  gap: 0.4rem;
  white-space: nowrap;
}
.sec-no::before {
  content: '';
  display: block;
  width: 1rem;
  height: 1px;
  background: var(--signal);
  opacity: var(--sec-no-before-opacity);
}

.sec-vline {
  width: 1px;
  flex: 1;
  background: linear-gradient(
    to bottom,
    var(--rule-mid) 0%,
    var(--rule) 60%,
    transparent 100%
  );
  min-height: 2rem;
}

/* ── type system ─────────────────────────────────────────────────── */
h1 {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(2.2rem, 1rem + 5.6vw, 5.0rem);
  line-height: 1.02;
  letter-spacing: -0.020em;
  max-width: 17ch;
  color: var(--ink);
}
h1 .hl {
  color: var(--signal);
}

h2 {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(1.65rem, 1.15rem + 1.9vw, 2.45rem);
  line-height: 1.07;
  letter-spacing: -0.014em;
  color: var(--ink);
}

h3 {
  font-family: var(--font-display);
  font-weight: 500;
  font-size: clamp(1.05rem, 0.92rem + 0.52vw, 1.28rem);
  line-height: 1.27;
  letter-spacing: -0.008em;
  color: var(--ink-mid);
  margin-top: calc(var(--u) * 8);
  max-width: 40ch;
}

strong { font-weight: 600; color: var(--ink); }
.runin {
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 0.84em;
  letter-spacing: 0.015em;
  color: var(--ink);
  text-transform: lowercase;
}

/* ── hero ────────────────────────────────────────────────────────── */
.sec--hero {
  display: block;
  position: relative;
  isolation: isolate;
  max-width: var(--wrap);
  margin-inline: auto;
  padding-inline: var(--pad);
  margin-top: clamp(3rem, 8vh, 6rem);
  margin-bottom: clamp(4rem, 10vh, 7rem);
}

.hero-instrument {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: calc(var(--u) * 6);
  font-family: var(--font-mono);
  font-size: 0.66rem;
  color: var(--hero-instrument-color);
  letter-spacing: 0.07em;
  max-width: 26rem;
}
.hero-gauge-label {
  color: var(--signal);
  font-weight: 700;
  letter-spacing: 0.11em;
}
.hero-gauge { flex: 1; display: flex; flex-direction: column; gap: 3px; }
.hero-gauge-bar {
  height: 4px;
  background: var(--hero-gauge-bar-bg);
  border: 1px solid var(--rule-mid);
  border-radius: 2px;
  overflow: hidden;
}
.hero-gauge-fill {
  height: 100%;
  width: 95%;
  background: linear-gradient(90deg, var(--signal-dim), var(--signal));
  border-radius: 2px;
  /* Gauge fill sweeps in once on load, part of the load choreography.
     transform (not width) so it's GPU-cheap and never reflows the gauge.
     `both` holds scaleX(0) through the delay; final/no-anim state is full. */
  transform-origin: left center;
  animation: gauge-sweep 1s cubic-bezier(0.16, 1, 0.3, 1) 0.2s both;
}
.hero-gauge-ticks {
  display: flex;
  gap: 0;
  height: 5px;
  align-items: flex-end;
}
.hero-gauge-ticks span {
  flex: 1;
  height: 3px;
  border-left: 1px solid var(--ink-faint);
}
.hero-gauge-ticks span.major {
  height: 5px;
  border-left-color: var(--signal-dim);
}
.hero-gauge-scale {
  display: flex;
  justify-content: space-between;
  font-size: 0.58rem;
  color: var(--ink-faint);
  letter-spacing: 0;
}
.hero-gauge-scale .signal { color: var(--signal); }

.sec--hero h1 { max-width: 16ch; }

/* ── hero schematic ghost: a neutral trace of classify → … → eval ─────
   Lives in the hero's negative space, behind the type. Fully neutral
   (no signal). Foreshadows the real architecture diagram in section 03. */
.sec--hero > .hero-schematic {
  position: absolute;
  top: 4rem;
  right: calc(-1.9 * var(--pad));
  width: min(40%, 600px);
  height: auto;
  z-index: 0;
  pointer-events: none;
  overflow: visible;
}
.sec--hero > :not(.hero-schematic) { position: relative; z-index: 1; }

.hero-schematic .gs-branch { fill: none; stroke: var(--rule);     stroke-width: 1; }
.hero-schematic .gs-spine  { fill: none; stroke: var(--ink-dim);  stroke-width: 1.4; }
.hero-schematic .gs-fb     { fill: none; stroke: var(--rule);     stroke-width: 1; stroke-dasharray: 5 3; }
.hero-schematic .gs-node   { fill: var(--ink-faint); }
.hero-schematic .gs-node-s { fill: var(--ink-dim); }
.hero-schematic .gs-via    { fill: none; stroke: var(--ink-faint); stroke-width: 1; }

/* draw-in is part of the one load choreography. Default (no-animation) state
   is fully drawn + visible, so reduced-motion / headless render shows the
   finished board, never a blank or half-drawn one. */
.hero-schematic .draw {
  stroke-dasharray: 100;
  stroke-dashoffset: 0;
  animation: ghost-draw 1.3s cubic-bezier(0.16, 1, 0.3, 1) 0.25s both;
}
.hero-schematic .gs-spine.draw { animation-duration: 1.8s; animation-delay: 0.45s; }
.hero-schematic .gs-fb { animation: ghost-fade 0.9s ease 1.5s both; }
.hero-schematic .gs-node,
.hero-schematic .gs-node-s,
.hero-schematic .gs-via { animation: ghost-fade 0.6s ease 1.0s both; }

.lede {
  font-family: var(--font-display);
  font-size: clamp(1.08rem, 0.93rem + 0.58vw, 1.26rem);
  line-height: 1.60;
  max-width: 52ch;
  margin-top: clamp(1.5rem, 3vh, 2.2rem);
  color: var(--ink-mid);
}

/* ── toc ─────────────────────────────────────────────────────────── */
.toc {
  margin-top: clamp(2.5rem, 6vh, 4rem);
  max-width: 56rem;
}
.toc-head {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 0.5rem;
}
.toc-label {
  font-family: var(--font-mono);
  font-size: 0.63rem;
  letter-spacing: 0.11em;
  color: var(--signal);
  font-weight: 700;
}
.toc-rule {
  flex: 1;
  height: 1px;
  background: var(--rule-mid);
}
.toc ol {
  list-style: none;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(18rem, 1fr));
  column-gap: 2rem;
}
.toc li {
  display: grid;
  grid-template-columns: 2.2rem 1fr;
  align-items: baseline;
  gap: 0.5rem;
  padding: calc(var(--u) * 2) 0;
  border-bottom: 1px solid var(--rule);
}
.toc-no {
  font-family: var(--font-mono);
  font-size: 0.66rem;
  letter-spacing: 0.05em;
  color: var(--signal);
  font-weight: 700;
}
.toc a {
  font-family: var(--font-display);
  font-weight: 400;
  font-size: 0.93rem;
  text-decoration: none;
  color: var(--ink-mid);
  transition: color 0.15s ease;
  letter-spacing: -0.004em;
}
.toc a:hover { color: var(--ink); }

/* ── claim blocks ────────────────────────────────────────────────── */
.claim-block {
  display: grid;
  grid-template-columns: 2.5rem 1fr;
  gap: 0 1rem;
  margin-top: calc(var(--u) * 8);
  padding-top: calc(var(--u) * 4);
  border-top: 1px solid var(--rule);
}
.claim-marker {
  padding-top: 0.15rem;
}
.claim-no-badge {
  font-family: var(--font-mono);
  font-size: 0.60rem;
  font-weight: 700;
  letter-spacing: 0.09em;
  color: var(--bg);
  background: var(--signal);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 1.6rem;
  height: 1.6rem;
  border-radius: 1px;
}
.claim-content h3 {
  margin-top: 0;
}
.claim-content p { max-width: 62ch; }
.claim-content p + p { margin-top: 0.85em; }

/* ── evidence section ────────────────────────────────────────────── */
.sec--evidence {
  border-top: 1px solid var(--rule-mid);
  border-bottom: 1px solid var(--rule-mid);
  background: var(--bg-raised);
  max-width: 100%;
  padding-block: clamp(4rem, 10vh, 6.5rem);
  margin-block: clamp(5rem, 12vh, 8rem);
  display: block;
}

.evidence-header {
  max-width: var(--wrap);
  margin-inline: auto;
  padding-inline: var(--pad);
  display: grid;
  grid-template-columns: var(--rail) minmax(0, 1fr);
  column-gap: var(--gap);
}
.evidence-header .sec-rail { grid-column: 1; }
.evidence-header .sec-body { grid-column: 2; }

.sec-body--continued {
  max-width: var(--wrap);
  margin-inline: auto;
  padding-right: var(--pad);
  padding-left: calc(var(--pad) + var(--rail) + var(--gap));
  margin-top: calc(var(--u) * 6);
}

/* ── exhibit container ───────────────────────────────────────────── */
.exhibit {
  max-width: var(--wrap);
  margin-inline: auto;
  padding-inline: var(--pad);
  margin-top: calc(var(--u) * 8);
}

.exhibit-cap {
  font-family: var(--font-mono);
  font-size: 0.73rem;
  line-height: 1.62;
  color: var(--ink-mid);
  border-top: 1px solid var(--rule-mid);
  margin-top: calc(var(--u) * 4);
  padding-top: calc(var(--u) * 3);
  max-width: 70ch;
}
.cap-label {
  font-weight: 700;
  color: var(--signal);
  margin-right: 0.75rem;
  letter-spacing: 0.02em;
}

/* ── architecture diagram ────────────────────────────────────────── */
.exhibit--diagram {
  background: var(--bg);
  border: 1px solid var(--rule-mid);
  border-radius: 2px;
  padding: calc(var(--u) * 6);
}

.dg { display: block; width: 100%; height: auto; }
.dg--v { display: none; max-width: 26rem; margin-inline: auto; }

.d-box {
  fill: var(--bg-box);
  stroke: var(--rule-mid);
  stroke-width: 1;
}
.d-box--signal {
  stroke: var(--signal);
  stroke-width: 1.5;
  fill: var(--signal-wash);
}
.d-box--ghost {
  fill: none;
  stroke: var(--ink-faint);
  stroke-width: 1;
  stroke-dasharray: 2 4;
}

.d-flow {
  fill: none;
  stroke: var(--d-flow-stroke);
  stroke-width: 1.25;
  marker-end: url(#ah-h);
}
.dg--v .d-flow { marker-end: url(#ah-v); }
.d-flow--signal {
  stroke: var(--signal);
  stroke-dasharray: 5 3;
  marker-end: url(#aha-h);
}
.dg--v .d-flow--signal { marker-end: url(#aha-v); }
.d-flow--soft {
  stroke: var(--ink-faint);
  stroke-dasharray: 2 4;
  marker-end: none;
}
.d-flow--loop {
  stroke: var(--signal);
  stroke-dasharray: 5 3;
  marker-end: url(#aha-h);
}
.d-flow--loopv {
  stroke: var(--signal);
  stroke-dasharray: 5 3;
  marker-end: url(#aha-v);
}

.d-arrow { fill: var(--d-arrow-fill); }
.d-arrow--signal { fill: var(--signal); }

.dg text { font-family: var(--font-mono); }
.d-label { font-size: 12px; fill: var(--ink); }
.d-label--signal { fill: var(--signal); }
.d-label--dim { fill: var(--d-label-dim-fill); }
.d-sub { font-size: 10px; fill: var(--d-sub-fill); }
.d-sub--signal { font-size: 10px; fill: var(--d-sub-signal-fill); }

/* ── eval exhibit ────────────────────────────────────────────────── */
.exhibit--data {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: clamp(1.5rem, 4vw, 3rem);
  /* center the (shorter) table + Delta-readout block against the taller plot,
     so the right column reads as intentional padding, not a void beneath it,
     while keeping the readout next to the data it summarizes */
  align-items: center;
}
.exhibit--data > .exhibit-cap { grid-column: 1 / -1; }

/* plot */
.plot-wrap {
  background: var(--bg);
  border: 1px solid var(--rule-mid);
  border-radius: 2px;
  padding: calc(var(--u) * 3);
}
.plot { display: block; width: 100%; height: auto; }
.plot .grid-h {
  stroke: var(--rule);
  stroke-width: 1;
}
.plot .grid-drop {
  stroke: var(--ink-faint);
  stroke-width: 1;
  stroke-dasharray: 2 4;
  opacity: 0.6;
}
.plot .axis { stroke: var(--plot-axis-stroke); stroke-width: 1.5; }
.plot .tick-maj { stroke: var(--ink-mid); stroke-width: 1.5; }
.plot .tick-min { stroke: var(--ink-dim); stroke-width: 1; }
.plot .frontier {
  fill: none;
  stroke: var(--signal);
  stroke-width: 1.5;
  stroke-linejoin: round;
  opacity: var(--plot-frontier-opacity);
}
.plot .dot { fill: var(--plot-dot-fill); }
.plot .dot--signal { fill: var(--signal); }
.plot text { font-family: var(--font-mono); }
.plot .p-val  { font-size: 13.5px; fill: var(--ink); font-weight: 700; }
.plot .p-name { font-size: 11px;   fill: var(--ink-mid); }
.plot .p-cost { font-size: 10px;   fill: var(--plot-p-cost-fill); }
.plot .a-lab  { font-size: 10.5px; fill: var(--ink-dim); }
.plot .a-title { font-size: 10.5px; fill: var(--ink-mid); letter-spacing: 0.05em; }

/* table */
.table-wrap {
  display: flex;
  flex-direction: column;
  gap: calc(var(--u) * 4);
}

.eval {
  width: 100%;
  border-collapse: collapse;
  font-family: var(--font-mono);
}
.eval thead th {
  font-size: 0.66rem;
  letter-spacing: 0.07em;
  text-transform: lowercase;
  color: var(--signal);
  border-bottom: 1px solid var(--rule-mid);
  padding: calc(var(--u) * 1) calc(var(--u) * 2);
  padding-left: 0;
  font-weight: 700;
  text-align: left;
}
.eval tbody th,
.eval tbody td {
  font-size: 0.80rem;
  padding: calc(var(--u) * 2) calc(var(--u) * 2);
  padding-left: 0;
  border-bottom: 1px solid var(--rule);
  color: var(--ink-mid);
  vertical-align: top;
}
.eval tbody th { color: var(--ink); font-weight: 400; }
.eval .num {
  text-align: right;
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.02em;
}
.eval tbody td.num:first-of-type {
  color: var(--signal);
  font-size: 0.86rem;
}
.row--best th, .row--best td { color: var(--ink); }
.row--best td.num:first-of-type {
  color: var(--signal);
}

/* delta readout: instrument-style computed diff */
.delta-readout {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: calc(var(--u) * 1) calc(var(--u) * 3);
  padding: calc(var(--u) * 3);
  background: var(--signal-wash);
  border: 1px solid var(--signal-dim);
  border-radius: 2px;
  font-family: var(--font-mono);
  align-items: baseline;
}
.delta-label {
  font-size: 0.64rem;
  letter-spacing: 0.05em;
  color: var(--delta-label-color);
  text-transform: lowercase;
}
.delta-value {
  font-size: 0.98rem;
  font-weight: 700;
  color: var(--signal);
  text-align: right;
  letter-spacing: 0.02em;
  font-variant-numeric: tabular-nums;
}

/* ── where I fit grid ────────────────────────────────────────────── */
.fit-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: calc(var(--u) * 4);
  margin-top: calc(var(--u) * 6);
  margin-bottom: calc(var(--u) * 6);
}
.fit-panel {
  padding: calc(var(--u) * 4);
  border: 1px solid var(--rule);
  border-radius: 2px;
  background: var(--bg-raised);
}
/* fit-panel--no is NOT dimmed: equal confidence to the YES panel per spec (never apology), and keeps body text AA in light mode. Differentiation is the dot color + SCOPE tag only. */
.fit-panel-head {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: calc(var(--u) * 3);
}
.fit-indicator {
  width: 8px; height: 8px;
  border-radius: 50%;
  flex-shrink: 0;
}
.fit-indicator--yes { background: var(--signal); }
.fit-indicator--no  { background: var(--ink-faint); }
.fit-tag {
  font-family: var(--font-mono);
  font-size: 0.63rem;
  letter-spacing: 0.09em;
  font-weight: 700;
}
.fit-panel--yes .fit-tag { color: var(--signal); }
.fit-panel--no  .fit-tag { color: var(--ink-dim); }
.fit-panel p { max-width: 36ch; font-size: 0.88rem; color: var(--ink); }
.fit-panel strong { color: var(--ink); font-weight: 600; }
.fit-panel p { margin-top: 0; }

/* ── cta ─────────────────────────────────────────────────────────── */
.sec--cta { margin-bottom: clamp(2.5rem, 6vh, 4rem); }
.sec--cta .sec-body p { max-width: 54ch; }

.cta-line { margin-top: calc(var(--u) * 8); }
.cta-mail {
  font-family: var(--font-mono);
  font-size: clamp(0.96rem, 0.82rem + 0.75vw, 1.38rem);
  color: var(--signal);
  text-decoration: none;
  display: inline-flex;
  align-items: baseline;
  gap: 0.5rem;
  border-bottom: 1px solid var(--signal-dim);
  padding-bottom: 0.15em;
  transition: border-color 0.15s ease, color 0.15s ease;
}
.cta-mail:hover {
  color: var(--ink);
  border-color: var(--ink-mid);
}
.cta-mail-prefix {
  font-size: 0.64em;
  letter-spacing: 0.09em;
  color: var(--cta-mail-prefix-color);
}

/* ── footer ──────────────────────────────────────────────────────── */
.foot {
  border-top: 1px solid var(--rule);
  margin-top: clamp(4rem, 10vh, 7rem);
}
.foot-inner {
  max-width: var(--wrap);
  margin-inline: auto;
  padding: calc(var(--u) * 3) var(--pad) calc(var(--u) * 6);
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.35rem 1.5rem;
  font-family: var(--font-mono);
  font-size: 0.70rem;
  color: var(--ink-faint);
}

/* ── entrance animation ──────────────────────────────────────────── */
@keyframes fadeup {
  from { opacity: 0; transform: translateY(10px); }
  to   { opacity: 1; transform: none; }
}
@keyframes gauge-sweep {
  from { transform: scaleX(0); }
  to   { transform: scaleX(1); }
}
@keyframes ghost-draw {
  from { stroke-dashoffset: 100; }
  to   { stroke-dashoffset: 0; }
}
@keyframes ghost-fade {
  from { opacity: 0; }
  to   { opacity: 1; }
}
.masthead         { animation: fadeup 0.5s cubic-bezier(0.16, 1, 0.3, 1) forwards; }
.sec--hero h1     { animation: fadeup 0.7s cubic-bezier(0.16, 1, 0.3, 1) 0.04s forwards; }
.sec--hero .lede  { animation: fadeup 0.7s cubic-bezier(0.16, 1, 0.3, 1) 0.11s forwards; }
.sec--hero .toc   { animation: fadeup 0.7s cubic-bezier(0.16, 1, 0.3, 1) 0.19s forwards; }

/* ── responsive ──────────────────────────────────────────────────── */
/* the hero ghost needs real right-side negative space; below this the
   headline grows wide enough to reach it, so retire it cleanly */
@media (max-width: 1200px) {
  .hero-schematic { display: none; }
}

@media (max-width: 900px) {
  .fit-grid       { grid-template-columns: 1fr; }
  .exhibit--data  { grid-template-columns: 1fr; }
}

@media (max-width: 760px) {
  .claim-block { grid-template-columns: 1fr; }
  .claim-marker { display: none; }
  .claim-content h3::before {
    content: attr(data-n) ' · ';
    font-family: var(--font-mono);
    font-size: 0.70rem;
    color: var(--signal);
    letter-spacing: 0.05em;
  }
}

@media (max-width: 700px) {
  .sec {
    grid-template-columns: 1fr;
    display: block;
  }
  .sec-rail {
    flex-direction: row;
    align-items: center;
    margin-bottom: calc(var(--u) * 3);
  }
  .sec-vline { display: none; }
  .sec-body { max-width: 100%; }

  .evidence-header { display: block; }
  .sec-body--continued { padding-left: var(--pad); }

  .dg--h { display: none; }
  .dg--v { display: block; }
}

@media (max-width: 560px) {
  .eval .col-latency { display: none; }
  .delta-readout { grid-template-columns: 1fr; gap: calc(var(--u) * 1); }
  .delta-value { text-align: left; font-size: 0.93rem; }
}

@media (max-width: 480px) {
  .masthead-readout .masthead-meta,
  .masthead-sep { display: none; }
  .hero-instrument { max-width: 100%; }

  /* stack theme switcher below masthead info on very small screens */
  .theme-switcher-wrap {
    order: 3;
    width: 100%;
    display: flex;
    justify-content: flex-start;
  }
}

/* ── reduced motion ──────────────────────────────────────────────── */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .masthead,
  .sec--hero h1,
  .sec--hero .lede,
  .sec--hero .toc,
  .hero-gauge-fill,
  .hero-schematic .draw,
  .hero-schematic .gs-fb,
  .hero-schematic .gs-node,
  .hero-schematic .gs-node-s,
  .hero-schematic .gs-via { animation: none; }
}

/* ── print ───────────────────────────────────────────────────────── */
@media print {
  :root {
    --bg:          #fff;
    --bg-raised:   #f5f5f5;
    --bg-box:      #ebebeb;
    --bg-rule:     #e0e0e0;
    --ink:         #111;
    --ink-mid:     #444;
    --ink-dim:     #666;
    --ink-faint:   #999;
    --signal:      #8a6800;
    --signal-dim:  #b38500;
    --signal-wash: #fff8e0;
    --rule:        #ddd;
    --rule-mid:    #ccc;
    --d-flow-stroke:        #777;
    --d-arrow-fill:         #777;
    --d-sub-fill:           #888;
    --d-sub-signal-fill:    #b38500;
    --d-label-dim-fill:     #666;
    --plot-dot-fill:        #666;
    --plot-p-cost-fill:     #b38500;
    --plot-axis-stroke:     #666;
    --plot-frontier-opacity: 1;
    --delta-label-color:    #b38500;
    --masthead-date-color:  #8a6800;
    --cta-mail-prefix-color: #b38500;
    --masthead-label-opacity: 1;
    --sec-no-before-opacity: 0.5;
    --hero-instrument-color: #8a6800;
    --hero-gauge-bar-bg:    #e0e0e0;
  }

  body { background: #fff; color: #111; }
  .skip, .tick-ruler, .foot-ticks, .theme-switcher-wrap, .hero-schematic { display: none; }
  .masthead { position: static; box-shadow: none; }
  .sec--evidence { background: #f9f9f9; border-color: #ddd; }

  .dg--h { display: block; }
  .dg--v { display: none; }

  .exhibit { break-inside: avoid; }
  h2, h3 { break-after: avoid; }
  .sec { margin-block: 2rem; }
  .sec--hero { margin-top: 1rem; margin-bottom: 2rem; }
  .masthead, .sec--hero h1, .sec--hero .lede, .sec--hero .toc, .hero-gauge-fill { animation: none; opacity: 1 !important; transform: none !important; }
  .sec, .exhibit, .sec--evidence { animation: none !important; opacity: 1 !important; transform: none !important; }
}