/* ==========================================================================
   MetaVie homepage — parent-brand visual system.
   Same hue family as OddLab (periwinkle #7181FD → violet #A084F1 on charcoal),
   re-derived for a light, bright surface. Brand tones are darkened so text and
   buttons pass WCAG AA on white; the OddLab values stay as tints/glows.
   ========================================================================== */

:root {
  color-scheme: light;

  --color-bg: #fafafc;
  --color-surface: #ffffff;
  --color-surface-alt: #f2f2fa;
  --color-ink: #1e1e24;              /* OddLab's deep charcoal, now the ink */
  --color-text-primary: #1e1e24;
  --color-text-secondary: #5b5d75;   /* 6.2:1 on bg */
  --color-text-tertiary: #6f7190;    /* 4.5:1 on bg */
  --color-brand-primary: #4f5fe6;    /* periwinkle, darkened: 4.9:1 on bg, 5.1:1 white-on */
  --color-brand-primary-hover: #4353d9;
  --color-brand-accent: #7a5fd9;     /* violet, darkened: 4.5:1 */
  --color-brand-tint: #7181fd;       /* OddLab primary — decorative only */
  --color-brand-tint-2: #a084f1;
  --color-brand-wash: rgba(113, 129, 253, 0.10);
  --color-brand-wash-strong: rgba(113, 129, 253, 0.18);
  --color-border: rgba(30, 30, 36, 0.10);
  --color-border-strong: rgba(30, 30, 36, 0.20);
  --color-focus: #4f5fe6;
  --color-on-brand: #ffffff;

  --font-display: ui-rounded, "SF Pro Rounded", "Nunito", -apple-system, "PingFang SC", "Hiragino Sans GB", "Noto Sans SC", sans-serif;
  --font-body: -apple-system, BlinkMacSystemFont, "Inter", "PingFang SC", "Hiragino Sans GB", "Noto Sans SC", "Segoe UI", sans-serif;
  --font-mono: "JetBrains Mono", "SF Mono", ui-monospace, Menlo, monospace;

  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.5rem;
  --space-6: 2rem;
  --space-7: 3rem;
  --space-8: 4.5rem;
  --section-gap: clamp(5rem, 12vw, 10rem);

  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --radius-pill: 999px;

  --shadow-soft: 0 1px 2px rgba(30, 30, 36, 0.04), 0 12px 32px rgba(30, 30, 36, 0.06);
  --shadow-card: 0 1px 2px rgba(30, 30, 36, 0.05), 0 24px 60px rgba(79, 95, 230, 0.10);
  --glow-brand: 0 0 90px rgba(113, 129, 253, 0.22);

  --content-max-width: 1180px;
  --gutter: clamp(1rem, 4vw, 2.5rem);
  --header-height: 68px;

  --ease-out: cubic-bezier(0.22, 1, 0.36, 1);
  --dur: 700ms;
}

/* ----------------------------------------------------------------- reset */
*,
*::before,
*::after {
  box-sizing: border-box;
}
html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}
body {
  margin: 0;
  background: var(--color-bg);
  color: var(--color-text-primary);
  font-family: var(--font-body);
  font-size: 1rem;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}
img,
svg {
  display: block;
  max-width: 100%;
}
a {
  color: inherit;
  text-decoration: none;
}
p,
dl,
dd,
figure {
  margin: 0;
}
h1,
h2,
h3 {
  margin: 0;
  font-weight: 400;
}
button {
  font: inherit;
  color: inherit;
}
[hidden] {
  display: none !important;
}
:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}
.visually-hidden {
  position: absolute !important;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}
.skip-link {
  position: absolute;
  top: -100px;
  left: var(--gutter);
  z-index: 100;
  padding: var(--space-2) var(--space-4);
  background: var(--color-brand-primary);
  color: var(--color-on-brand);
  border-radius: var(--radius-sm);
}
.skip-link:focus {
  top: var(--space-3);
}
.container {
  width: 100%;
  max-width: var(--content-max-width);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

/* ------------------------------------------------------------ typography */
.display-xl,
.display-lg {
  font-family: var(--font-display);
  font-weight: 700;
  letter-spacing: -0.015em;
  line-height: 1.08;
  text-wrap: balance;
}
.display-xl {
  font-size: clamp(2.5rem, 6vw, 4.9rem);
}
.display-lg {
  font-size: clamp(1.9rem, 4vw, 3.1rem);
}
.display-lg em {
  font-style: normal;
  color: var(--color-brand-primary);
}
.wordmark {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 1.35rem;
  letter-spacing: -0.02em;
  color: var(--color-ink);
}
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: var(--space-3);
  font-family: var(--font-mono);
  font-size: 0.76rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-text-secondary);
  margin-bottom: var(--space-6);
}
.eyebrow-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--color-brand-primary);
  box-shadow: 0 0 0 4px var(--color-brand-wash);
}
.section-label {
  display: inline-flex;
  align-items: center;
  gap: var(--space-3);
  font-family: var(--font-mono);
  font-size: 0.74rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-text-secondary);
  margin-bottom: var(--space-6);
}
.label-index {
  padding: 2px 8px;
  border: 1px solid var(--color-border-strong);
  border-radius: var(--radius-sm);
  color: var(--color-brand-primary);
}
.section-intro {
  margin-top: var(--space-5);
  color: var(--color-text-secondary);
  font-size: 1.1rem;
  max-width: 50ch;
}
.muted {
  color: var(--color-text-secondary);
}
.muted a {
  color: var(--color-brand-primary);
  text-decoration: underline;
  text-underline-offset: 3px;
}
.callout {
  padding-left: var(--space-5);
  border-left: 2px solid var(--color-brand-primary);
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.3rem;
  line-height: 1.3;
  color: var(--color-ink);
}
.annotation-code {
  font-family: var(--font-mono);
  font-size: 0.66rem;
  letter-spacing: 0.12em;
  color: var(--color-text-tertiary);
  margin-right: var(--space-3);
}

/* --------------------------------------------------------------- buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  min-height: 50px;
  padding: 0 var(--space-6);
  border-radius: var(--radius-pill);
  border: 1px solid transparent;
  font-weight: 600;
  white-space: nowrap;
  transition: transform 200ms var(--ease-out), background-color 200ms, border-color 200ms, box-shadow 200ms, color 200ms;
}
.btn:hover {
  transform: translateY(-1px);
}
.btn-primary {
  background: var(--color-brand-primary);
  color: var(--color-on-brand);
}
.btn-primary:hover {
  background: var(--color-brand-primary-hover);
  box-shadow: 0 10px 28px rgba(79, 95, 230, 0.28);
}
.btn-ghost {
  border-color: var(--color-border-strong);
  color: var(--color-ink);
  background: transparent;
}
.btn-ghost:hover {
  border-color: var(--color-brand-primary);
  color: var(--color-brand-primary);
}

/* ---------------------------------------------------------------- header */
.site-header {
  position: sticky;
  top: env(safe-area-inset-top, 0px);
  z-index: 50;
  height: var(--header-height);
  background: rgba(250, 250, 252, 0.8);
  -webkit-backdrop-filter: saturate(140%) blur(14px);
  backdrop-filter: saturate(140%) blur(14px);
  border-bottom: 1px solid var(--color-border);
}
.header-inner {
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-5);
}
.site-nav {
  display: flex;
  gap: var(--space-6);
  font-size: 0.95rem;
  color: var(--color-text-secondary);
}
.site-nav a {
  padding: var(--space-2) 0;
  border-bottom: 1px solid transparent;
  transition: color 150ms, border-color 150ms;
}
.site-nav a:hover {
  color: var(--color-ink);
  border-color: var(--color-brand-primary);
}
.header-actions {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}
.lang-select {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  min-height: 40px;
  padding: 0 var(--space-3);
  border: 1px solid var(--color-border-strong);
  border-radius: var(--radius-pill);
  background: var(--color-surface);
  color: var(--color-text-secondary);
  cursor: pointer;
  transition: border-color 150ms, color 150ms;
}
.lang-select:hover,
.lang-select:focus-within {
  border-color: var(--color-brand-primary);
  color: var(--color-ink);
}
.lang-select:focus-within {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
}
.lang-select-icon {
  width: 18px;
  height: 18px;
  fill: currentColor;
  flex: 0 0 auto;
}
.lang-select-chevron {
  width: 14px;
  height: 14px;
  flex: 0 0 auto;
  pointer-events: none;
}
.lang-select-input {
  -webkit-appearance: none;
  appearance: none;
  background: transparent;
  border: 0;
  padding: 0;
  margin: 0;
  color: inherit;
  font: inherit;
  font-size: 0.9rem;
  cursor: pointer;
  max-width: 9.5rem;
}
.lang-select-input:focus-visible {
  outline: none;
}
.header-cta {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.06em;
  color: var(--color-brand-primary);
  white-space: nowrap;
}

/* ------------------------------------------------------------------ hero */
.hero {
  position: relative;
  padding-block: clamp(4rem, 10vw, 8.5rem) clamp(4rem, 8vw, 6rem);
  overflow: hidden;
}
.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background:
    radial-gradient(55% 45% at 85% 20%, var(--color-brand-wash), transparent 70%),
    radial-gradient(35% 35% at 70% 90%, rgba(160, 132, 241, 0.10), transparent 70%);
  pointer-events: none;
}
.hero::after {
  /* faint lab grid */
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(to right, rgba(30, 30, 36, 0.045) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(30, 30, 36, 0.045) 1px, transparent 1px);
  background-size: 48px 48px;
  -webkit-mask-image: radial-gradient(70% 70% at 60% 40%, #000 20%, transparent 80%);
  mask-image: radial-gradient(70% 70% at 60% 40%, #000 20%, transparent 80%);
  pointer-events: none;
}
.hero-grid {
  position: relative;
  display: grid;
  grid-template-columns: minmax(0, 1.4fr) minmax(0, 0.8fr);
  align-items: end;
  gap: clamp(2rem, 6vw, 5rem);
}
.hero-copy .display-xl {
  max-width: 14ch;
}
.hero-lead {
  margin-top: var(--space-6);
  max-width: 46ch;
  font-size: clamp(1.1rem, 1.6vw, 1.3rem);
  color: var(--color-text-secondary);
}
.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-4);
  margin-top: var(--space-7);
}
.hero-log {
  padding: var(--space-5);
  border: 1px dashed var(--color-border-strong);
  border-radius: var(--radius-md);
  background: rgba(255, 255, 255, 0.6);
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--color-text-secondary);
}
.log-title {
  letter-spacing: 0.14em;
  text-transform: uppercase;
  font-size: 0.66rem;
  color: var(--color-text-tertiary);
  margin-bottom: var(--space-4);
}
.log-list div {
  display: grid;
  grid-template-columns: 7.5rem 1fr;
  gap: var(--space-3);
  padding-block: var(--space-2);
  border-top: 1px solid var(--color-border);
}
.log-list dt {
  color: var(--color-text-tertiary);
}
.log-list dd {
  color: var(--color-ink);
}
.log-list a {
  color: var(--color-brand-primary);
  text-decoration: underline;
  text-underline-offset: 3px;
}
.log-chain {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  margin-top: var(--space-5);
  padding-top: var(--space-4);
  border-top: 1px solid var(--color-border);
  font-size: 0.7rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--color-brand-primary);
}
.chain-arrow {
  color: var(--color-text-tertiary);
}

/* -------------------------------------------------------------- sections */
.section {
  padding-block: var(--section-gap);
  border-top: 1px solid var(--color-border);
}

/* exploring */
.exploring-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.1fr) minmax(0, 0.9fr);
  gap: clamp(2rem, 6vw, 6rem);
  align-items: start;
}
.exploring-body {
  display: flex;
  flex-direction: column;
  gap: var(--space-5);
  font-size: 1.08rem;
  color: var(--color-text-secondary);
  padding-top: 0.5rem;
}
.exploring-body .callout {
  margin-block: var(--space-2);
}

/* how I build */
.how {
  background: var(--color-surface);
}
.how-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: clamp(2rem, 6vw, 6rem);
  align-items: center;
}
.how-body {
  display: flex;
  flex-direction: column;
  gap: var(--space-5);
  margin-top: var(--space-6);
  font-size: 1.08rem;
  color: var(--color-text-secondary);
  max-width: 46ch;
}
.build-loop {
  position: relative;
  width: min(440px, 100%);
  aspect-ratio: 1;
  margin-inline: auto;
}
.loop-svg {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  transform: rotate(-90deg);
}
.loop-track {
  fill: none;
  stroke: var(--color-border-strong);
  stroke-width: 1.5;
  stroke-dasharray: 3 7;
}
.loop-progress {
  fill: none;
  stroke: var(--color-brand-primary);
  stroke-width: 2.5;
  stroke-linecap: round;
  stroke-dasharray: 942;
  stroke-dashoffset: 942;
}
.build-loop.is-inview .loop-progress {
  animation: loop-draw 6s linear infinite;
}
.loop-arrow path {
  fill: none;
  stroke: var(--color-brand-primary);
  stroke-width: 2.5;
  stroke-linecap: round;
  stroke-linejoin: round;
}
.loop-steps {
  list-style: none;
  margin: 0;
  padding: 0;
  position: absolute;
  inset: 0;
}
.loop-step,
.loop-center {
  position: absolute;
  display: flex;
  flex-direction: column;
  gap: 2px;
  padding: 10px 14px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-soft);
  min-width: 132px;
}
.step-code {
  font-family: var(--font-mono);
  font-size: 0.62rem;
  letter-spacing: 0.14em;
  color: var(--color-text-tertiary);
}
.step-name {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.1rem;
  line-height: 1.15;
  color: var(--color-ink);
}
.step-note {
  font-size: 0.78rem;
  color: var(--color-text-secondary);
}
.step-1 { top: 2%; left: 50%; transform: translateX(-50%); }
.step-2 { top: 50%; right: -2%; transform: translateY(-50%); }
.step-3 { bottom: 2%; left: 50%; transform: translateX(-50%); }
.step-4 { top: 50%; left: -2%; transform: translateY(-50%); }
.loop-center {
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  align-items: center;
  text-align: center;
  max-width: 150px;
  min-width: 0;
  border-color: var(--color-brand-primary);
  background: var(--color-brand-wash);
  box-shadow: none;
}
.loop-center .step-name {
  color: var(--color-brand-primary);
}

/* work / experiments */
.work-head {
  max-width: 60ch;
  margin-bottom: var(--space-8);
}
.experiment {
  padding: clamp(1.5rem, 4vw, 3rem);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background: var(--color-surface);
  box-shadow: var(--shadow-soft);
}
.experiment + .experiment {
  margin-top: var(--space-6);
}
.experiment-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  margin-bottom: var(--space-6);
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-text-tertiary);
}
.status {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 4px 10px;
  border-radius: var(--radius-pill);
  border: 1px solid var(--color-border);
  color: var(--color-text-secondary);
}
.status-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--color-text-tertiary);
}
.status-active .status-dot {
  background: var(--color-brand-primary);
  box-shadow: 0 0 0 3px var(--color-brand-wash);
}
.status-lab .status-dot {
  background: var(--color-brand-accent);
  animation: pulse 2.2s ease-in-out infinite;
}
.experiment-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: clamp(2rem, 5vw, 5rem);
  align-items: center;
}
.experiment-brand {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  margin-bottom: var(--space-5);
}
.experiment-logo {
  width: 56px;
  height: 56px;
  border-radius: 14px;
  flex: 0 0 auto;
}
.experiment-logo-text {
  display: grid;
  place-items: center;
  background: var(--color-surface-alt);
  border: 1px solid var(--color-border);
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 1.5rem;
  color: var(--color-brand-accent);
}
.experiment-name {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 1.75rem;
  letter-spacing: -0.01em;
  line-height: 1.1;
}
.experiment-tagline {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
}
.experiment-question {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(1.3rem, 2.2vw, 1.7rem);
  line-height: 1.25;
  letter-spacing: -0.01em;
}
.experiment-desc {
  margin-top: var(--space-4);
  color: var(--color-text-secondary);
  font-size: 1.05rem;
  max-width: 52ch;
}
.experiment-specs {
  margin-top: var(--space-5);
  margin-bottom: var(--space-6);
  font-size: 0.92rem;
}
.experiment-specs div {
  display: grid;
  grid-template-columns: 6.5rem 1fr;
  gap: var(--space-4);
  padding-block: var(--space-3);
  border-top: 1px solid var(--color-border);
}
.experiment-specs dt {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-text-tertiary);
  padding-top: 3px;
}
.experiment-note {
  font-family: var(--font-mono);
  font-size: 0.74rem;
  color: var(--color-text-tertiary);
}
.experiment-visual {
  position: relative;
}
.visual-caption {
  margin-top: var(--space-4);
  font-size: 0.8rem;
  color: var(--color-text-secondary);
  text-align: center;
}

/* OddLab visual: the product keeps its own dark surface inside the light page */
.oddlab-frame {
  width: min(280px, 80%);
  margin-inline: auto;
  padding: 26px 14px;
  aspect-ratio: 9 / 16;
  border-radius: 36px;
  background: radial-gradient(120% 70% at 50% 0%, #2f2f36 0%, #1e1e24 60%, #16161a 100%);
  box-shadow: var(--shadow-card), var(--glow-brand);
  display: grid;
  place-items: center;
  overflow: hidden;
}
.oddlab-bodygraph {
  width: 100%;
  height: auto;
  filter: drop-shadow(0 0 16px rgba(113, 129, 253, 0.28));
}

/* Speak visual: the chain */
.chain {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  align-items: stretch;
  gap: 0;
  max-width: 300px;
  margin-inline: auto;
}
.chain-node {
  position: relative;
  padding: 14px 18px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-surface);
  box-shadow: var(--shadow-soft);
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.05rem;
  color: var(--color-ink);
  display: flex;
  align-items: center;
  gap: var(--space-3);
}
.chain-node + .chain-node {
  margin-top: 22px;
}
.chain-node + .chain-node::before {
  content: "";
  position: absolute;
  top: -22px;
  left: 50%;
  width: 1px;
  height: 22px;
  background: linear-gradient(var(--color-border-strong), var(--color-brand-accent));
}
.chain-node-out {
  border-color: var(--color-brand-accent);
  background: rgba(122, 95, 217, 0.08);
}
.chain-code {
  font-family: var(--font-mono);
  font-size: 0.62rem;
  letter-spacing: 0.14em;
  color: var(--color-text-tertiary);
}

/* notes rail */
.notes {
  background: var(--color-surface);
}
.notes-head {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: var(--space-6);
  margin-bottom: var(--space-7);
}
.rail-controls {
  display: flex;
  gap: var(--space-2);
  flex: 0 0 auto;
}
.rail-btn {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: 1px solid var(--color-border-strong);
  background: var(--color-surface);
  cursor: pointer;
  color: var(--color-ink);
  transition: border-color 150ms, color 150ms;
}
.rail-btn:hover {
  border-color: var(--color-brand-primary);
  color: var(--color-brand-primary);
}
.rail-wrap {
  position: relative;
}
.rail {
  list-style: none;
  margin: 0;
  padding: var(--space-2) var(--gutter) var(--space-5);
  display: flex;
  gap: var(--space-5);
  overflow-x: auto;
  scroll-snap-type: x mandatory;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
}
.rail::-webkit-scrollbar {
  display: none;
}
.rail > li {
  flex: 0 0 clamp(260px, 30vw, 360px);
  scroll-snap-align: start;
}
.rail:empty {
  display: none;
}
.note-card {
  display: block;
  border-radius: var(--radius-md);
  overflow: hidden;
  border: 1px solid var(--color-border);
  background: var(--color-surface);
  box-shadow: var(--shadow-soft);
  transition: transform 200ms var(--ease-out), box-shadow 200ms;
}
.note-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-card);
}
.note-thumb {
  position: relative;
  aspect-ratio: 16 / 9;
  background: var(--color-surface-alt);
}
.note-thumb img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}
.note-play {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
}
.note-play span {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.92);
  display: grid;
  place-items: center;
  color: var(--color-ink);
  box-shadow: var(--shadow-soft);
}
.note-body {
  padding: var(--space-4) var(--space-5) var(--space-5);
}
.note-meta {
  font-family: var(--font-mono);
  font-size: 0.66rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-text-tertiary);
}
.note-title {
  margin-top: var(--space-2);
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.1rem;
  line-height: 1.3;
}
.note-desc {
  margin-top: var(--space-2);
  font-size: 0.9rem;
  color: var(--color-text-secondary);
}
.rail-empty {
  max-width: var(--content-max-width);
  margin-inline: auto;
  padding: var(--space-6) var(--gutter);
}
.rail-empty-title {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.25rem;
}
.rail-empty-body {
  margin-top: var(--space-2);
  color: var(--color-text-secondary);
}
.upcoming {
  list-style: none;
  margin: var(--space-4) 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: var(--space-3);
}
.upcoming li {
  padding: var(--space-3) var(--space-4);
  border: 1px dashed var(--color-border-strong);
  border-radius: var(--radius-md);
  font-size: 0.92rem;
  color: var(--color-text-secondary);
  display: flex;
  gap: var(--space-3);
  align-items: baseline;
}
.upcoming .annotation-code {
  margin: 0;
}

/* about */
.about-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: clamp(2rem, 6vw, 6rem);
  align-items: start;
}
.about-body {
  display: flex;
  flex-direction: column;
  gap: var(--space-5);
  font-size: 1.1rem;
  color: var(--color-text-secondary);
  padding-top: 0.5rem;
}
.about-facts {
  margin-top: var(--space-3);
  font-size: 0.95rem;
}
.about-facts div {
  display: grid;
  grid-template-columns: 8rem 1fr;
  gap: var(--space-4);
  padding-block: var(--space-3);
  border-top: 1px solid var(--color-border);
}
.about-facts dt {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-text-tertiary);
  padding-top: 3px;
}
.about-facts dd {
  color: var(--color-ink);
}
.about-facts a {
  color: var(--color-brand-primary);
  text-decoration: underline;
  text-underline-offset: 3px;
}

/* ---------------------------------------------------------------- footer */
.site-footer {
  border-top: 1px solid var(--color-border);
  background: var(--color-surface-alt);
  padding-block: var(--space-8) var(--space-6);
  padding-bottom: calc(var(--space-6) + env(safe-area-inset-bottom, 0px));
}
.footer-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.6fr) repeat(3, minmax(0, 1fr));
  gap: var(--space-6);
}
.footer-tagline {
  margin-top: var(--space-2);
  font-size: 0.9rem;
  color: var(--color-text-secondary);
}
.footer-heading {
  font-family: var(--font-mono);
  font-size: 0.66rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--color-text-tertiary);
  margin-bottom: var(--space-3);
}
.footer-col a,
.footer-muted {
  display: block;
  padding-block: var(--space-2);
  font-size: 0.95rem;
  color: var(--color-text-secondary);
}
.footer-col a {
  text-decoration: underline;
  text-decoration-color: var(--color-border-strong);
  text-underline-offset: 4px;
}
.footer-col a:hover {
  color: var(--color-brand-primary);
  text-decoration-color: var(--color-brand-primary);
}
.footer-muted {
  color: var(--color-text-tertiary);
}
.footer-bottom {
  margin-top: var(--space-7);
  padding-top: var(--space-5);
  border-top: 1px solid var(--color-border);
  font-size: 0.82rem;
  color: var(--color-text-secondary);
}
.footer-legal {
  margin-top: var(--space-2);
  font-size: 0.74rem;
  color: var(--color-text-tertiary);
}

/* ---------------------------------------------------------------- motion */
@keyframes pulse {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.45; transform: scale(0.8); }
}
@keyframes loop-draw {
  0% { stroke-dashoffset: 942; opacity: 1; }
  85% { stroke-dashoffset: 0; opacity: 1; }
  100% { stroke-dashoffset: 0; opacity: 0; }
}
.reveal {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity var(--dur) var(--ease-out), transform var(--dur) var(--ease-out);
}
.reveal.is-inview {
  opacity: 1;
  transform: none;
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal { opacity: 1; transform: none; transition: none; }
  .build-loop.is-inview .loop-progress { animation: none; stroke-dashoffset: 0; }
  .status-lab .status-dot { animation: none; }
  .btn:hover, .note-card:hover { transform: none; }
}

/* ------------------------------------------------------------ responsive */
@media (max-width: 1024px) {
  .hero-grid { grid-template-columns: 1fr; align-items: start; }
  .hero-log { max-width: 520px; }
  .exploring-grid, .how-grid, .about-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .footer-brand { grid-column: 1 / -1; }
}
@media (max-width: 900px) {
  .site-nav { display: none; }
  .experiment-grid, .experiment-grid-flip { grid-template-columns: 1fr; }
  .experiment-grid-flip .experiment-visual { order: 1; }
  .notes-head { flex-direction: column; align-items: flex-start; }
  .rail-controls { display: none; }
}
@media (max-width: 600px) {
  :root { --header-height: 60px; }
  .header-cta { display: none; }
  .hero-actions .btn { width: 100%; }
  .build-loop { width: 100%; }
  .loop-step, .loop-center { min-width: 0; padding: 8px 10px; }
  .step-note { display: none; }
  .step-name { font-size: 0.95rem; }
  .step-2 { right: 0; }
  .step-4 { left: 0; }
  .log-list div { grid-template-columns: 6rem 1fr; }
  .experiment { border-radius: var(--radius-md); }
  .experiment-specs div, .about-facts div { grid-template-columns: 1fr; gap: var(--space-1); }
  .footer-grid { grid-template-columns: 1fr; }
  .rail > li { flex-basis: 78vw; }
}