/*
  Birch HTML Design System
  Opinionated single-option stylesheet for reliable LLM-generated artifacts.

  Model:
    1. Design tokens as CSS variables.
    2. Layout primitives as classes.
    3. Semantic components as classes with data-* variants.
*/

/* ==================== 1. TOKENS ==================== */

:root {
  color-scheme: light;

  /* Palette */
  --color-ivory: #FAF9F5;
  --color-slate: #141413;
  --color-clay: #D97757;
  --color-clay-dark: #B85C3E;
  --color-oat: #E3DACC;
  --color-olive: #788C5D;
  --color-rust: #B04A3F;
  --color-sky: #6A8CAF;
  --color-white: #FFFFFF;

  --color-gray-50: #F7F5EE;
  --color-gray-100: #F0EEE6;
  --color-gray-150: #E8E4DA;
  --color-gray-200: #DED9CD;
  --color-gray-300: #D1CFC5;
  --color-gray-500: #87867F;
  --color-gray-700: #3D3D3A;
  --color-gray-800: #242421;

  /* Semantic colors */
  --bg: var(--color-white);
  --surface: var(--color-white);
  --surface-tint: var(--color-gray-100);
  --surface-warm: var(--color-gray-100);
  --text: var(--color-slate);
  --text-muted: var(--color-gray-500);
  --text-soft: var(--color-gray-700);
  --muted: var(--text-muted);
  --border-color: var(--color-gray-300);
  --accent: var(--color-clay);
  --accent-strong: var(--color-clay-dark);
  --success: var(--color-olive);
  --warning: #C78E3F;
  --danger: var(--color-rust);
  --info: var(--color-sky);

  /* Typography */
  --font-serif: ui-serif, Georgia, "Times New Roman", serif;
  --font-sans: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --font-mono: ui-monospace, "SF Mono", Menlo, Consolas, monospace;

  --text-xs: 11px;
  --text-sm: 12px;
  --text-md: 14px;
  --text-base: 15px;
  --text-lg: 17px;
  --text-xl: 21px;
  --text-2xl: 26px;
  --text-3xl: 36px;
  --text-4xl: 44px;

  --leading-tight: 1.15;
  --leading-title: 1.25;
  --leading-body: 1.55;
  --leading-loose: 1.7;

  /* Spacing */
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 24px;
  --space-6: 32px;
  --space-7: 48px;
  --space-8: 64px;
  --space-9: 96px;

  /* Shape */
  --radius-xs: 4px;
  --radius-sm: 6px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 20px;
  --radius-pill: 999px;

  --border: 1.5px solid var(--border-color);
  --border-thin: 1px solid var(--border-color);

  --shadow-sm: none;
  --shadow-md: none;
  --shadow-lg: none;

  /* Motion */
  --ease: cubic-bezier(0.2, 0, 0, 1);
  --ease-spring: cubic-bezier(0.34, 1.56, 0.64, 1);
  --dur-fast: 120ms;
  --dur: 180ms;
  --hover-y: 0;

  /* Page sizing */
  --page-max: 1100px;
  --page-pad: 28px;
  --page-pad-block: 48px;

  /* Legacy aliases used by source examples */
  --ivory: var(--color-ivory);
  --slate: var(--color-slate);
  --clay: var(--color-clay);
  --clay-d: var(--color-clay-dark);
  --oat: var(--color-oat);
  --olive: var(--color-olive);
  --rust: var(--color-rust);
  --sky: var(--color-sky);
  --white: var(--color-white);
  --gray-50: var(--color-gray-50);
  --gray-100: var(--color-gray-100);
  --gray-150: var(--color-gray-150);
  --gray-200: var(--color-gray-200);
  --gray-300: var(--color-gray-300);
  --gray-500: var(--color-gray-500);
  --gray-700: var(--color-gray-700);
  --gray-800: var(--color-gray-800);
  --serif: var(--font-serif);
  --sans: var(--font-sans);
  --mono: var(--font-mono);
}

/* ==================== BASE ==================== */

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

html {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

img,
svg {
  max-width: 100%;
}

a {
  color: inherit;
  text-decoration-color: rgba(217, 119, 87, 0.45);
  text-underline-offset: 3px;
}

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

h1,
h2,
h3,
p {
  margin-block: 0;
}

h1,
h2,
h3 {
  font-family: var(--font-sans);
  font-weight: 600;
  letter-spacing: -0.005em;
  line-height: var(--leading-title);
}

h1 {
  font-size: clamp(32px, 5vw, var(--text-4xl));
}

h2 {
  font-size: var(--text-2xl);
}

h3 {
  font-size: var(--text-xl);
}

code,
kbd,
pre {
  font-family: var(--font-mono);
}

code {
  font-size: 0.92em;
  white-space: normal;
  word-break: normal;
}

h1 code,
h2 code,
h3 code {
  overflow-wrap: anywhere;
  word-break: break-word;
}

button,
input,
textarea,
select {
  font: inherit;
}

button {
  cursor: pointer;
}

::selection {
  background: rgba(217, 119, 87, 0.24);
}

/* ==================== 2. LAYOUT PRIMITIVES ==================== */

.page {
  width: min(100% - (var(--page-pad) * 2), var(--page-max));
  margin-inline: auto;
  padding-block: var(--page-pad-block) var(--space-9);
}

.page[data-size="narrow"] {
  --page-max: 820px;
}

.page[data-size="wide"] {
  --page-max: 1280px;
}

.page[data-size="full"] {
  --page-max: 1440px;
}

.section {
  margin-block: var(--section-gap, var(--space-5));
}

.section[data-gap="lg"] {
  --section-gap: var(--space-6);
}

.section[data-gap="xl"] {
  --section-gap: var(--space-7);
}

.section:first-child {
  margin-block-start: 0;
}

.stack > .section {
  margin-block: 0;
}

.rule {
  border: 0;
  border-top: var(--border-thin);
  margin: var(--space-3) 0 var(--space-5);
}

.stack {
  display: flex;
  flex-direction: column;
  gap: var(--stack-gap, var(--space-4));
}

.stack[data-gap="xs"] { --stack-gap: var(--space-2); }
.stack[data-gap="sm"] { --stack-gap: var(--space-3); }
.stack[data-gap="md"] { --stack-gap: var(--space-4); }
.stack[data-gap="lg"] { --stack-gap: var(--space-6); }
.stack[data-gap="xl"] { --stack-gap: var(--space-8); }

.stack > :is(.button, .btn, .chip, .badge) {
  align-self: flex-start;
}

.cluster {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--cluster-gap, var(--space-3));
}

.cluster[data-align="start"] { align-items: flex-start; }
.cluster[data-align="end"] { align-items: flex-end; }
.cluster[data-justify="between"] { justify-content: space-between; }
.cluster[data-justify="end"] { justify-content: flex-end; }

.grid {
  display: grid;
  gap: var(--grid-gap, var(--space-5));
}

.grid[data-cols="2"] {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.grid[data-cols="3"] {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.grid[data-cols="4"] {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

.auto-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, var(--grid-min, 240px)), 1fr));
  gap: var(--grid-gap, var(--space-5));
}

.auto-grid > * {
  min-width: 0;
}

.split {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(280px, var(--split-side, 360px));
  gap: var(--split-gap, var(--space-6));
  align-items: start;
}

.split > * {
  min-width: 0;
}

.section-head {
  min-width: 0;
}

.section-rail {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(280px, var(--rail-width, 360px));
  column-gap: var(--rail-gap, var(--space-6));
  row-gap: var(--space-5);
  align-items: start;
}

.section-rail > .section-head {
  grid-column: 1 / -1;
}

.section-rail > .reference-panel,
.section-rail > aside {
  align-self: start;
}

.sidebar-layout {
  display: grid;
  grid-template-columns: var(--sidebar-width, 240px) minmax(0, 1fr);
  gap: var(--sidebar-gap, var(--space-7));
  align-items: start;
}

.sidebar-layout > :first-child,
.sticky {
  position: sticky;
  top: var(--sticky-top, var(--space-5));
}

.bleed {
  margin-inline: calc(var(--page-pad) * -1);
}

.scroll-x {
  overflow-x: auto;
  overscroll-behavior-inline: contain;
}

.center {
  display: grid;
  place-items: center;
}

.spacer {
  flex: 1;
}

@media (max-width: 860px) {
  :root {
    --page-pad: 20px;
    --page-pad-block: 40px;
  }

  .grid[data-cols],
  .split,
  .section-rail,
  .sidebar-layout {
    grid-template-columns: 1fr;
  }

  .sidebar-layout > :first-child,
  .sticky {
    position: static;
  }
}

/* ==================== TYPOGRAPHY UTILITIES ==================== */

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  color: var(--text-muted);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.lede {
  color: var(--text-soft);
  font-size: var(--text-lg);
  line-height: 1.6;
}

.muted {
  color: var(--text-muted);
}

.caption {
  color: var(--text-muted);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
}

.stat-value {
  display: block;
  color: var(--text);
  font-family: var(--font-sans);
  font-size: var(--text-2xl);
  font-variant-numeric: tabular-nums;
  font-weight: 700;
  letter-spacing: -0.01em;
  line-height: 1;
}

.stat-card {
  gap: var(--space-2);
}

.stat-card .caption {
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.stat-card .muted {
  max-width: 34ch;
  font-size: var(--text-sm);
}

.mono {
  font-family: var(--font-mono);
}

/* ==================== 3. SEMANTIC COMPONENTS ==================== */

.panel,
.card {
  background: var(--surface);
  border: var(--border);
  border-radius: var(--radius-md);
}

.panel {
  padding: var(--panel-pad, var(--space-5));
}

.card {
  padding: var(--card-pad, var(--space-5));
  transition:
    transform var(--dur-fast) var(--ease),
    border-color var(--dur-fast) var(--ease),
    box-shadow var(--dur-fast) var(--ease),
    background-color var(--dur-fast) var(--ease);
}

.card[data-hover="lift"]:hover,
.card[data-clickable]:hover {
  border-color: var(--text-muted);
}

.card[data-clickable] {
  cursor: pointer;
}

.card[data-variant="flat"] {
  background: transparent;
  border-color: transparent;
  box-shadow: none;
}

.card[data-variant="outlined"] {
  background: var(--surface);
  border: var(--border);
}

.card[data-variant="elevated"] {
  border-color: transparent;
  box-shadow: var(--shadow-md);
}

.card[data-variant="filled"],
.card[data-tone="oat"] {
  background: var(--surface-warm);
}

.card[data-tone],
.panel[data-tone],
.callout[data-tone] {
  background: var(--surface);
}

.card[data-tone="danger"],
.panel[data-tone="danger"],
.callout[data-tone="danger"] {
  border-color: rgba(176, 74, 63, 0.36);
}

.card[data-tone="warning"],
.panel[data-tone="warning"],
.callout[data-tone="warning"] {
  border-color: rgba(199, 142, 63, 0.38);
}

.card[data-tone="success"],
.panel[data-tone="success"],
.callout[data-tone="success"] {
  border-color: rgba(120, 140, 93, 0.38);
}

.card[data-tone="info"],
.panel[data-tone="info"],
.callout[data-tone="info"] {
  border-color: rgba(106, 140, 175, 0.36);
}

.card-head {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  min-width: 0;
  max-width: 100%;
}

.card-head > :first-child {
  flex: 0 0 auto;
}

.card-titles {
  flex: 1 1 0;
  min-width: 0;
  max-width: 100%;
}

.card-title {
  max-width: 100%;
  margin: 0;
  font-family: var(--font-sans);
  font-size: var(--text-xl);
  font-weight: 600;
  line-height: var(--leading-title);
  overflow-wrap: anywhere;
}

.card-sub {
  margin: 2px 0 0;
  color: var(--text-muted);
  font-size: var(--text-sm);
  overflow-wrap: anywhere;
}

.toolbar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-4);
  padding: var(--space-4) var(--space-5);
  background: var(--surface);
  border: var(--border);
  border-radius: var(--radius-md);
}

.toolbar[data-sticky] {
  position: sticky;
  top: 0;
  z-index: 10;
}

.chip,
.badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  border-radius: var(--radius-xs);
  white-space: nowrap;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 650;
  line-height: 1;
}

.chip {
  min-height: 24px;
  padding: 0 10px;
  color: var(--text-soft);
  background: var(--surface-tint);
  border: 1px solid transparent;
}

.badge {
  min-height: 22px;
  padding: 0 9px;
  color: var(--text-muted);
  background: var(--surface);
  border: var(--border-thin);
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.chip[data-tone="clay"],
.badge[data-tone="clay"] {
  color: var(--accent);
  background: rgba(217, 119, 87, 0.14);
}

.chip[data-tone="olive"],
.badge[data-tone="olive"],
.chip[data-tone="success"],
.badge[data-tone="success"] {
  color: var(--success);
  background: rgba(120, 140, 93, 0.15);
}

.chip[data-tone="warning"],
.badge[data-tone="warning"] {
  color: var(--warning);
  background: rgba(199, 142, 63, 0.16);
}

.chip[data-tone="rust"],
.badge[data-tone="rust"],
.chip[data-tone="danger"],
.badge[data-tone="danger"] {
  color: var(--danger);
  background: rgba(176, 74, 63, 0.13);
}

.chip[data-tone="sky"],
.badge[data-tone="sky"],
.chip[data-tone="info"],
.badge[data-tone="info"] {
  color: var(--info);
  background: rgba(106, 140, 175, 0.14);
}

.finding {
  border-left: 6px solid var(--border-color);
}

.finding[data-severity="blocker"],
.finding[data-severity="critical"],
.finding[data-severity="danger"],
.finding[data-tone="danger"] {
  border-left-color: var(--danger);
}

.finding[data-severity="high"],
.finding[data-severity="warning"],
.finding[data-tone="warning"] {
  border-left-color: var(--warning);
}

.finding[data-severity="medium"],
.finding[data-severity="info"],
.finding[data-tone="info"] {
  border-left-color: var(--info);
}

.finding[data-severity="low"],
.finding[data-severity="success"],
.finding[data-tone="success"] {
  border-left-color: var(--success);
}

.button,
.btn {
  appearance: none;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 36px;
  padding: 0 14px;
  border: 1.5px solid transparent;
  border-radius: var(--radius-sm);
  font-family: var(--font-sans);
  font-size: var(--text-md);
  font-weight: 650;
  line-height: 1;
  text-decoration: none;
  transition:
    transform var(--dur-fast) var(--ease),
    background-color var(--dur-fast) var(--ease),
    border-color var(--dur-fast) var(--ease),
    box-shadow var(--dur-fast) var(--ease);
}

.button:hover,
.btn:hover {
  filter: brightness(0.97);
}

.button[data-variant="primary"],
.btn-primary {
  color: var(--color-white);
  background: var(--color-slate);
}

.button[data-variant="primary"]:hover,
.btn-primary:hover {
  background: var(--color-gray-700);
}

.button[data-variant="secondary"],
.btn-secondary {
  color: var(--text);
  background: var(--surface-tint);
  border-color: var(--border-color);
}

.button[data-variant="ghost"],
.btn-ghost {
  color: var(--text-soft);
  background: transparent;
}

.button[data-variant="ghost"]:hover,
.btn-ghost:hover {
  color: var(--text);
  background: var(--surface-tint);
}

.button[data-variant="danger"],
.btn-danger {
  color: var(--color-white);
  background: var(--danger);
}

.input {
  width: 100%;
  min-height: 38px;
  padding: 0 12px;
  color: var(--text);
  background: var(--surface);
  border: var(--border);
  border-radius: var(--radius-sm);
  outline: none;
}

.input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(217, 119, 87, 0.16);
}

.avatar {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: var(--avatar-size, 38px);
  height: var(--avatar-size, 38px);
  border-radius: 50%;
  color: var(--text-soft);
  background: var(--surface-warm);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: 700;
  letter-spacing: 0.02em;
  flex: 0 0 auto;
}

.code-block {
  margin: 0;
  padding: var(--space-4) var(--space-5);
  overflow-x: auto;
  color: #E8E6DC;
  background: var(--color-slate);
  border-radius: var(--radius-md);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  line-height: var(--leading-loose);
}

.code-block[data-kind="command"],
.code-block[data-wrap="true"],
.command-block {
  max-width: 100%;
  min-width: 0;
  box-sizing: border-box;
  white-space: pre-wrap;
  overflow-wrap: anywhere;
  word-break: break-word;
  overflow-x: hidden;
}

.code-block[data-wrap="true"] code,
.code-block[data-kind="command"] code {
  display: block;
  max-width: 100%;
  white-space: pre-wrap;
  overflow-wrap: anywhere;
  word-break: break-word;
}

.copyable {
  position: relative;
}

.copyable > .code-block {
  padding-inline-end: 88px;
}

.copy-button {
  appearance: none;
  position: absolute;
  inset-block-start: var(--space-2);
  inset-inline-end: var(--space-2);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 26px;
  padding: 0 9px;
  border: 1px solid rgba(250, 249, 245, 0.18);
  border-radius: var(--radius-sm);
  color: var(--color-gray-100);
  background: rgba(255, 255, 255, 0.08);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  transition:
    background-color var(--dur-fast) var(--ease),
    border-color var(--dur-fast) var(--ease),
    transform var(--dur-fast) var(--ease);
}

.copy-button:hover {
  border-color: rgba(250, 249, 245, 0.35);
  background: rgba(255, 255, 255, 0.14);
}

.copy-button[data-copied="true"] {
  color: var(--color-white);
  background: rgba(120, 140, 93, 0.55);
  border-color: rgba(120, 140, 93, 0.75);
}

.reference-panel {
  --panel-pad: var(--space-5);
}

.callout {
  padding: var(--space-5);
  color: var(--text-soft);
  background: var(--surface-tint);
  border: var(--border);
  border-inline-start: 4px solid var(--accent);
  border-radius: var(--radius-md);
}

.callout[data-tone="success"] {
  border-inline-start-color: var(--success);
  background: rgba(120, 140, 93, 0.10);
}

.callout[data-tone="warning"] {
  border-inline-start-color: var(--warning);
  background: rgba(199, 142, 63, 0.11);
}

.callout[data-tone="danger"] {
  border-inline-start-color: var(--danger);
  background: rgba(176, 74, 63, 0.10);
}

.callout[data-tone="info"] {
  border-inline-start-color: var(--info);
  background: rgba(106, 140, 175, 0.11);
}

.callout-label {
  display: block;
  margin-bottom: var(--space-2);
  color: var(--text-muted);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 700;
  letter-spacing: 0.09em;
  text-transform: uppercase;
}

.callout > :last-child {
  margin-bottom: 0;
}

.checklist {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: var(--space-3);
}

.checklist li {
  display: block !important;
  position: relative !important;
  min-width: 0;
  padding-inline-start: calc(18px + var(--space-3));
  overflow-wrap: anywhere;
}

.checklist li::before {
  content: "✓";
  position: absolute !important;
  inset-block-start: 2px;
  inset-inline-start: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  color: var(--success);
  background: rgba(120, 140, 93, 0.12);
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 700;
  line-height: 1;
}

.checklist code {
  white-space: normal;
  overflow-wrap: anywhere;
  word-break: break-word;
}

.plain-list {
  margin: 0;
  padding-inline-start: 1.15em;
  color: var(--text-soft);
}

.plain-list li {
  overflow-wrap: anywhere;
}

.plain-list li + li {
  margin-top: var(--space-2);
}

.plain-list li::marker {
  color: var(--text-muted);
}

.insight-list,
.takeaway-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: var(--space-3);
}

.insight-list li,
.takeaway-list li {
  position: relative;
  display: block;
  padding-inline-start: calc(10px + var(--space-3));
  color: var(--text-soft);
}

.insight-list li::before,
.takeaway-list li::before {
  content: "";
  position: absolute;
  inset-block-start: 0.65em;
  inset-inline-start: 0;
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--accent);
}

.insight-list li > *,
.takeaway-list li > * {
  min-width: 0;
}

.insight-list[data-tone="success"] li::before,
.takeaway-list[data-tone="success"] li::before {
  background: var(--success);
}

.insight-list[data-tone="info"] li::before,
.takeaway-list[data-tone="info"] li::before {
  background: var(--info);
}

.metric-list {
  --metric-label: 132px;
  --metric-value: 64px;
  display: grid;
  gap: var(--space-3);
}

.metric-row {
  display: grid;
  grid-template-columns: var(--metric-label) minmax(120px, 1fr) var(--metric-value);
  gap: var(--space-3);
  align-items: center;
}

.metric-row > :first-child {
  min-width: 0;
}

.metric-row > :last-child {
  justify-self: end;
  font-family: var(--font-mono);
  font-size: var(--text-sm);
}

.meter {
  height: 9px;
  overflow: hidden;
  border-radius: var(--radius-pill);
  background: var(--surface-tint);
}

.meter span {
  display: block;
  width: var(--value);
  height: 100%;
  background: var(--tone, var(--accent));
}

.flow-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: var(--space-3);
}

.flow-step {
  position: relative;
  display: grid;
  grid-template-columns: 42px minmax(0, 1fr);
  gap: var(--space-3);
  align-items: start;
  padding: var(--space-4);
  background: var(--surface);
  border: var(--border);
  border-radius: var(--radius-md);
}

.flow-step > .flow-num {
  grid-column: 1;
}

.flow-step > :not(.flow-num) {
  grid-column: 2;
  min-width: 0;
}

.flow-step::after {
  content: "";
  position: absolute;
  inset-block-start: calc(100% + 1px);
  inset-inline-start: 36px;
  width: 1.5px;
  height: var(--space-3);
  background: var(--border-color);
}

.flow-step:last-child::after {
  display: none;
}

.flow-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 34px;
  border-radius: var(--radius-pill);
  color: var(--text);
  background: var(--surface-warm);
  box-shadow: inset 0 0 0 1px rgba(20, 20, 19, 0.10);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: 700;
}

.flow-title {
  margin: 0 0 var(--space-1);
  font-family: var(--font-sans);
  font-size: var(--text-xl);
  font-weight: 600;
  line-height: var(--leading-title);
}

.flow-detail {
  margin: 0;
  color: var(--text-soft);
}

.flow-branch {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--space-3);
}

.flow-branch .flow-step::after {
  display: none;
}

.flow-step[data-tone="success"] {
  border-color: rgba(120, 140, 93, 0.38);
  background: rgba(120, 140, 93, 0.08);
}

.flow-step[data-tone="warning"] {
  border-color: rgba(199, 142, 63, 0.42);
  background: rgba(199, 142, 63, 0.09);
}

@media (max-width: 620px) {
  .metric-row {
    grid-template-columns: 1fr max-content;
  }

  .metric-row .meter {
    grid-column: 1 / -1;
    order: 3;
  }

  .flow-branch {
    grid-template-columns: 1fr;
  }
}

/* ---------- Charts and numeric data ---------- */

.chart-panel {
  max-width: 100%;
  min-width: 0;
  overflow: hidden;
}

.chart-panel > * {
  min-width: 0;
}

.chart-panel svg,
svg.chart-svg {
  display: block;
  width: 100%;
  height: auto;
}

.chart-caption {
  color: var(--text-muted);
  font-size: var(--text-sm);
}

.numeric-table-wrap {
  overflow-x: auto;
  background: var(--surface);
  border: var(--border);
  border-radius: var(--radius-md);
}

.numeric-table {
  width: 100%;
  min-width: 720px;
  border-collapse: collapse;
}

.numeric-table th,
.numeric-table td {
  padding: var(--space-3) var(--space-4);
  border-bottom: 1px solid var(--color-gray-200);
  vertical-align: middle;
}

.numeric-table th {
  color: var(--text-muted);
  background: var(--surface-tint);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 700;
  letter-spacing: 0.08em;
  text-align: left;
  text-transform: uppercase;
}

.numeric-table tr:last-child td {
  border-bottom: 0;
}

.numeric-table .metric,
.numeric-table .num {
  text-align: right;
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}

.numeric-table .entity,
.numeric-table .label-cell {
  font-weight: 650;
}

.numeric-table .note {
  color: var(--text-soft);
}

.numeric-table code {
  white-space: normal;
  overflow-wrap: anywhere;
  word-break: break-word;
}

.numeric-table .subtle {
  display: block;
  margin-top: 2px;
  color: var(--text-muted);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 400;
}

@media (max-width: 620px) {
  .numeric-table {
    min-width: 0;
  }

  .numeric-table thead {
    display: none;
  }

  .numeric-table tbody,
  .numeric-table tr,
  .numeric-table td {
    display: block;
  }

  .numeric-table tr {
    padding: var(--space-3) var(--space-4);
    border-bottom: 1px solid var(--color-gray-200);
  }

  .numeric-table tr:last-child {
    border-bottom: 0;
  }

  .numeric-table td {
    padding: var(--space-1) 0;
    border-bottom: 0;
  }

  .numeric-table td[data-label] {
    display: flex;
    justify-content: space-between;
    gap: var(--space-4);
  }

  .numeric-table td[data-label]::before {
    content: attr(data-label);
    color: var(--text-muted);
    font-family: var(--font-mono);
    font-size: var(--text-xs);
    text-transform: uppercase;
  }
}

/* ---------- Diff ---------- */

.diff {
  overflow-x: auto;
  color: #E8E6DC;
  background: var(--color-slate);
  border-radius: var(--radius-md);
  font-family: var(--font-mono);
  font-size: 12.5px;
  line-height: var(--leading-loose);
}

.diff-row {
  display: grid;
  grid-template-columns: 48px 18px minmax(max-content, 1fr);
  align-items: baseline;
  min-width: max-content;
  padding-inline-end: var(--space-4);
  white-space: pre;
}

.diff-row .ln {
  padding-inline-end: 14px;
  color: var(--color-gray-500);
  text-align: right;
  user-select: none;
}

.diff-row .mark {
  color: var(--color-gray-500);
  text-align: center;
}

.diff-row .code {
  color: #E8E6DC;
}

.diff-row.ctx .code,
.diff-row[data-kind="ctx"] .code {
  color: #B8B6AC;
}

.diff-row.add,
.diff-row[data-kind="add"] {
  background: rgba(120, 140, 93, 0.24);
  box-shadow: inset 3px 0 0 rgba(120, 140, 93, 0.78);
}

.diff-row.add .mark,
.diff-row[data-kind="add"] .mark {
  color: #B9D394;
  font-weight: 800;
}

.diff-row.del,
.diff-row[data-kind="del"] {
  background: rgba(176, 74, 63, 0.24);
  box-shadow: inset 3px 0 0 rgba(176, 74, 63, 0.82);
}

.diff-row.del .mark,
.diff-row[data-kind="del"] .mark {
  color: #F19A8D;
  font-weight: 800;
}

.diff-row.hunk,
.diff-row[data-kind="hunk"] {
  background: rgba(255, 255, 255, 0.045);
}

.diff-row.hunk .code,
.diff-row[data-kind="hunk"] .code {
  color: var(--color-gray-500);
}

.diff[data-wrap="true"] {
  overflow-x: hidden;
}

.diff[data-wrap="true"] .diff-row {
  grid-template-columns: 42px 18px minmax(0, 1fr);
  min-width: 0;
  white-space: normal;
}

.diff[data-wrap="true"] .code {
  white-space: pre-wrap;
  overflow-wrap: anywhere;
}

/* ---------- Timeline ---------- */

.timeline {
  position: relative;
  display: grid;
  gap: 0;
  padding-inline-start: var(--space-6);
}

.timeline:is(ol, ul) {
  margin: 0;
  list-style: none;
}

.timeline::before {
  content: "";
  position: absolute;
  inset-block: 4px 4px;
  inset-inline-start: 9px;
  width: 1.5px;
  background: var(--border-color);
}

.timeline-item,
.tl-entry {
  position: relative;
  display: grid;
  grid-template-columns: minmax(84px, max-content) minmax(0, 1fr);
  gap: var(--space-4);
  padding-block: 0 var(--space-5);
}

.timeline-item:last-child,
.tl-entry:last-child {
  padding-block-end: 0;
}

.timeline-item::before,
.tl-entry::before {
  content: "";
  position: absolute;
  inset-block-start: 4px;
  inset-inline-start: calc(4.25px - var(--space-6));
  width: 11px;
  height: 11px;
  border: 2px solid var(--surface);
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 1.5px var(--accent);
}

.timeline-item:not(:has(> .timeline-time, > .tl-time)),
.tl-entry:not(:has(> .timeline-time, > .tl-time)) {
  display: block;
}

.timeline-time,
.tl-time {
  color: var(--text-muted);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  white-space: nowrap;
}

.timeline-body,
.tl-body {
  min-width: 0;
  color: var(--text-soft);
}

.timeline-body strong,
.tl-body strong {
  color: var(--text);
}

@media (max-width: 620px) {
  .timeline-item,
  .tl-entry {
    grid-template-columns: 1fr;
    gap: var(--space-1);
  }
}

/* ---------- Flowchart ---------- */

.flowchart {
  display: block;
  width: 100%;
  height: auto;
}

svg.flow,
svg.flowchart {
  display: block;
  width: 100%;
  height: auto;
}

.flow text,
.flowchart text {
  fill: var(--text);
  font-family: var(--font-sans);
  font-size: 12px;
}

.flow .sub,
.flowchart .sub {
  fill: var(--text-muted);
  font-size: 10px;
}

.flow-edge,
.edge {
  fill: none;
  stroke: var(--text-muted);
  stroke-width: 1.5;
}

.flow-edge[data-kind="yes"],
.edge.yes {
  stroke: var(--success);
}

.flow-edge[data-kind="no"],
.edge.no {
  stroke: var(--danger);
  stroke-dasharray: 4 4;
}

/* SVG flow nodes */
.flow-node,
.flow .node {
  cursor: pointer;
  transition: transform var(--dur-fast) var(--ease);
}

.flow-node:hover,
.flow .node:hover {
  opacity: 0.9;
}

.flow-node rect,
.flow .node rect {
  fill: var(--surface);
  stroke: var(--border-color);
  stroke-width: 1.5;
  rx: 8;
}

.flow-node path,
.flow .node.gate path {
  fill: var(--surface);
  stroke: var(--border-color);
  stroke-width: 1.5;
}

.flow-node[data-shape="term"] rect,
.flow .node.term rect {
  fill: var(--surface-tint);
  rx: 22;
}

.flow-node[data-kind="ok"] rect,
.flow .node.ok rect {
  fill: rgba(120, 140, 93, 0.12);
  stroke: var(--success);
}

.flow-node[data-kind="bad"] rect,
.flow .node.bad rect {
  fill: rgba(176, 74, 63, 0.10);
  stroke: var(--danger);
}

.flow-node.active rect,
.flow-node.active path,
.flow .node.active rect,
.flow .node.active path {
  stroke: var(--accent);
  stroke-width: 2;
}

/* HTML flow nodes, for non-SVG diagrams */
div.flow-node {
  padding: var(--space-3) var(--space-4);
  background: var(--surface);
  border: var(--border);
  border-radius: var(--radius-sm);
  transition:
    transform var(--dur-fast) var(--ease),
    border-color var(--dur-fast) var(--ease),
    box-shadow var(--dur-fast) var(--ease);
}

div.flow-node:hover {
  border-color: var(--text-muted);
}

div.flow-node[data-shape="term"] {
  border-radius: var(--radius-pill);
  background: var(--surface-tint);
}

div.flow-node[data-kind="ok"] {
  border-color: var(--success);
  background: rgba(120, 140, 93, 0.12);
}

div.flow-node[data-kind="bad"] {
  border-color: var(--danger);
  background: rgba(176, 74, 63, 0.10);
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
  }
}

/* Responsive safety net for generated artifacts. */
p,
li {
  overflow-wrap: anywhere;
}

@media (max-width: 860px) {
  .split,
  .section-rail,
  .sidebar-layout {
    grid-template-columns: minmax(0, 1fr) !important;
  }

  .split > *,
  .section-rail > *,
  .sidebar-layout > *,
  .chart-panel {
    width: 100%;
    max-width: 100%;
    min-width: 0;
  }
}

/* ==================== PAGE-LOCAL OVERRIDES ==================== */

      /* page-local: larger, higher-contrast type using Birch tokens */
      :root {
        --text-muted: var(--color-gray-700);   /* darker than gray-500 for readable "muted" text */
        --text-xs: 12.5px;
        --text-sm: 13.5px;
        --text-md: 15px;
      }
      .lede { color: var(--text); }
      .caption, .card-sub, .muted, .chart-caption { color: var(--text-soft); }
      .numeric-table th { color: var(--text-soft); }
      .numeric-table .subtle { color: var(--text-soft); font-size: var(--text-sm); }
      .code-block { font-size: 13.5px; }
      /* keep prose-y survey cells wrapping on mobile */
      .numeric-table td .subtle { white-space: normal; }
      .numeric-table code, .numeric-table .note { white-space: normal; overflow-wrap: anywhere; word-break: break-word; }

/* ==================== VARIANTS — per-survey colour schemes ==================== */
/* The client and server surveys tag their A/B/C/D groups with data-variant
   instead of a shared semantic tone, so the two pages read as distinct colour
   families. The palette is selected by a page-level class on <main>
   (.variants-client / .variants-server); .variants scopes the component rules. */

.variants-client {
  --variant-a: #3F77A6;   /* blue   */
  --variant-b: #4E8C8A;   /* teal   */
  --variant-c: #5E6CA8;   /* indigo */
  --variant-d: #788C5D;   /* olive  */
}

.variants-server {
  --variant-a: #C78E3F;   /* amber */
  --variant-b: #D97757;   /* clay  */
  --variant-c: #B04A3F;   /* rust  */
  --variant-d: #8A5A7A;   /* plum  */
}

.variants [data-variant="a"] { --variant: var(--variant-a); }
.variants [data-variant="b"] { --variant: var(--variant-b); }
.variants [data-variant="c"] { --variant: var(--variant-c); }
.variants [data-variant="d"] { --variant: var(--variant-d); }

.variants .badge[data-variant],
.variants .chip[data-variant] {
  color: var(--variant);
  background: color-mix(in srgb, var(--variant) 15%, transparent);
}

.variants .card[data-variant] {
  border-color: color-mix(in srgb, var(--variant) 40%, transparent);
}

.variants .card[data-variant][data-accent] {
  --accent: var(--variant);
}