/**
 * Product landing page design system.
 *
 * Light, neutral-greyscale theme built on the shadcn/ui "neutral" palette,
 * matching https://rbuild.ai. Generalised from the Ramify landing page
 * (github.com/RagnarPitla/chess-local-learning) so a new product can reuse
 * it verbatim: no product-specific selectors remain.
 *
 * Three rules this file exists to enforce:
 *
 * 1. No build step, no imports, no external assets, no hosted fonts. Drop
 *    this file next to index.html and it works. A landing page that needs
 *    npm install is a landing page that rots.
 * 2. Monochrome is the point. The only colour outside the neutral scale is
 *    the --status-* set, reserved for real product data (a pass/fail dot, a
 *    severity label). Never use it for decoration. The moment a landing page
 *    reaches for a gradient it stops looking like an engineering tool.
 * 3. Accessibility is not a pass at the end. Focus outlines are never
 *    removed, contrast pairs are verified below and recorded in comments,
 *    and motion respects prefers-reduced-motion.
 *
 * Contrast, verified against #ffffff:
 *   --foreground        #0a0a0a  19.80:1  (AAA)
 *   --muted-foreground  #737373   4.74:1  (AA, body text and labels)
 *   --border            #e5e5e5   1.27:1  (decorative only, never text)
 * Reversed, verified against --primary #171717:
 *   --primary-foreground #fafafa 16.79:1  (AAA)
 */

:root {
  color-scheme: light;

  /* ---------------------------------------------------------- surfaces */
  --background: #ffffff;
  --foreground: #0a0a0a;
  --card: #ffffff;
  --card-foreground: #0a0a0a;

  /* ----------------------------------------------------------- actions */
  --primary: #171717;
  --primary-foreground: #fafafa;
  --secondary: #f5f5f5;
  --secondary-foreground: #171717;

  /* ------------------------------------------------------ neutral fill */
  --muted: #f5f5f5;
  --muted-foreground: #737373;
  --accent: #f5f5f5;
  --accent-foreground: #171717;

  /* --------------------------------------------------------- structure */
  --border: #e5e5e5;
  --input: #e5e5e5;
  --ring: #0a0a0a;
  --radius: 0.5rem;
  --radius-sm: calc(var(--radius) - 4px);
  --radius-md: calc(var(--radius) - 2px);
  --radius-lg: var(--radius);
  --radius-xl: calc(var(--radius) + 4px);
  --radius-full: 999px;

  /* ------------------------------------------------------------ status
   * The one exception to the neutral scale. Reserved for small dots and
   * labels on real product data only, never decoration. Each clears WCAG
   * AA (4.5:1) on white so 13-15px label text is legible on its own.
   * Verified: ok 5.02:1, warn 5.02:1, bad 4.83:1 against #ffffff.
   */
  --status-ok: #15803d;
  --status-warn: #b45309;
  --status-bad: #dc2626;

  /* ------------------------------------------------------------- fonts */
  --font-sans: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", monospace;

  /* ----------------------------------------------------------- shadows
   * Minimal by design. These two are the only elevation used anywhere.
   */
  --shadow-xs: 0 1px 2px 0 rgb(0 0 0 / 0.04);
  --shadow-sm: 0 1px 3px 0 rgb(0 0 0 / 0.06), 0 1px 2px -1px rgb(0 0 0 / 0.06);

  --max: 1120px;
}

* { box-sizing: border-box; }

html { color-scheme: light; scroll-behavior: smooth; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  * {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
}

body {
  margin: 0;
  background: var(--background);
  color: var(--foreground);
  font: 16px/1.6 var(--font-sans);
  -webkit-font-smoothing: antialiased;
}

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

/* Body-copy links: underlined, monochrome. No colour accent in this theme. */
a { color: var(--foreground); text-decoration-color: var(--border); text-underline-offset: 3px; }
a:hover { text-decoration-color: currentColor; text-decoration-thickness: 2px; }

/* Consistent, visible keyboard focus everywhere - never remove the outline. */
a:focus-visible,
button:focus-visible,
summary:focus-visible {
  outline: 2px solid var(--ring);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}

h1, h2, h3 { font-weight: 650; line-height: 1.2; margin: 0 0 .5em; color: var(--foreground); }
h1 { font-size: clamp(28px, 5vw, 46px); letter-spacing: -0.01em; }
h2 { font-size: clamp(22px, 3.4vw, 30px); letter-spacing: -0.01em; }
h3 { font-size: 18px; }
p { margin: 0 0 1em; }

/* Line length is a readability control, not a preference. 62ch is the cap. */
.lede { font-size: 19px; color: var(--muted-foreground); max-width: 62ch; }

.container { max-width: var(--max); margin: 0 auto; padding: 0 22px; }
section { padding: 72px 0; border-bottom: 1px solid var(--border); }
section:last-of-type { border-bottom: none; }

/* Alternating tint bands give the page rhythm using greyscale value alone.
   Add .band to any section you want tinted; keep them non-adjacent. */
.band { background: var(--muted); }

/* -------------------------------------------------------------- skip link */

.skip-link {
  position: absolute;
  left: 12px;
  top: -60px;
  background: var(--primary);
  color: var(--primary-foreground);
  padding: 10px 16px;
  border-radius: var(--radius-md);
  font-weight: 700;
  z-index: 100;
  transition: top .15s ease;
}
.skip-link:focus { top: 12px; }

/* -------------------------------------------------------------- site head */

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(255, 255, 255, 0.88);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
}
@supports not (backdrop-filter: blur(1px)) {
  .site-header { background: var(--background); }
}
.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding-top: 14px;
  padding-bottom: 14px;
  flex-wrap: wrap;
}

.wordmark { display: flex; align-items: center; gap: 10px; text-decoration: none; color: var(--foreground); }
.wordmark-icon { flex: 0 0 auto; display: block; }
.wordmark .mark { font-size: 22px; font-weight: 800; letter-spacing: -0.02em; color: var(--foreground); }
.wordmark .strap { font-size: 13px; color: var(--muted-foreground); align-self: baseline; }
.wordmark:hover .mark { text-decoration: underline; text-underline-offset: 3px; }

@media (max-width: 620px) {
  .wordmark .strap { display: none; }
}

.site-nav ul { list-style: none; display: flex; gap: 4px; margin: 0; padding: 0; flex-wrap: wrap; align-items: center; }
.site-nav a {
  display: inline-block;
  padding: 8px 12px;
  border-radius: var(--radius-md);
  color: var(--muted-foreground);
  text-decoration: none;
  font-size: 14px;
  font-weight: 600;
}
.site-nav a:hover { color: var(--foreground); background: var(--muted); }
.site-nav a.cta { color: var(--primary-foreground); background: var(--primary); }
.site-nav a.cta:hover { filter: brightness(1.25); color: var(--primary-foreground); background: var(--primary); }

/* -------------------------------------------------------------------- hero */

.hero { padding-top: 56px; }
.hero .container {
  display: grid;
  grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
  gap: 48px;
  align-items: center;
}
@media (max-width: 860px) {
  .hero .container { grid-template-columns: 1fr; }
  .hero-art { order: -1; }
}

.hero h1 { margin-bottom: .4em; }
.hero .sub-line { font-size: 18px; color: var(--muted-foreground); max-width: 58ch; }
.hero .sub-line strong { color: var(--foreground); }

.cta-row { display: flex; gap: 12px; flex-wrap: wrap; margin: 26px 0 14px; }
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  border-radius: var(--radius-md);
  padding: 13px 20px;
  font-size: 15px;
  font-weight: 700;
  text-decoration: none;
  border: 1px solid var(--border);
  cursor: pointer;
}
.btn.primary { background: var(--primary); border-color: var(--primary); color: var(--primary-foreground); }
.btn.primary:hover { filter: brightness(1.25); }
.btn.ghost { background: transparent; color: var(--foreground); }
.btn.ghost:hover { background: var(--accent); border-color: var(--foreground); }

.microcopy { font-size: 13px; color: var(--muted-foreground); }
/* Mid-section heading, one level under the section h2. Sits far enough from the
   preceding paragraph to read as a new beat rather than a continuation. */
.sub-heading { font-size: 19px; font-weight: 600; letter-spacing: -.01em; margin: 40px 0 10px; }
.microcopy .sep { margin: 0 8px; opacity: .5; }

.hero-art { display: flex; align-items: center; justify-content: center; }
.hero-art svg { width: 100%; height: auto; }

/* ------------------------------------------------------------------ badges */

.badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font: 700 12px/1 var(--font-mono);
  padding: 7px 12px;
  border-radius: var(--radius-full);
  background: var(--primary);
  color: var(--primary-foreground);
}
/* Outline variant, for stating a status honestly rather than selling it. */
.badge.outline { background: transparent; color: var(--foreground); border: 1px solid var(--border); }

/* ------------------------------------------------------------------- prose */

.prose-section .container { max-width: 860px; }
.prose-section p { font-size: 17px; color: var(--foreground); }
.prose-section p.muted { color: var(--muted-foreground); }
.muted { color: var(--muted-foreground); }

/* --------------------------------------------------------------- how-steps */

.steps {
  list-style: none;
  margin: 40px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 18px;
  counter-reset: step;
}
@media (max-width: 900px) { .steps { grid-template-columns: 1fr 1fr; } }
@media (max-width: 560px) { .steps { grid-template-columns: 1fr; } }

/* Three-step variant. Add .steps-3 alongside .steps. */
.steps.steps-3 { grid-template-columns: repeat(3, 1fr); }
@media (max-width: 900px) { .steps.steps-3 { grid-template-columns: 1fr; } }

.steps li {
  counter-increment: step;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-xs);
  padding: 20px 18px;
  position: relative;
}
.steps li::before {
  content: counter(step);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 30px;
  height: 30px;
  border-radius: 50%;
  background: var(--primary);
  color: var(--primary-foreground);
  font: 800 14px/1 var(--font-mono);
  margin-bottom: 14px;
}
.steps h3 { margin-bottom: 6px; }
.steps p { color: var(--muted-foreground); font-size: 14.5px; margin-bottom: 0; }
.steps-loop {
  margin-top: 18px;
  color: var(--muted-foreground);
  font-size: 14px;
  display: flex;
  align-items: center;
  gap: 8px;
}
.steps-loop .loop-icon { flex: 0 0 auto; color: var(--foreground); }

/* -------------------------------------------------------------------- jobs */

.jobs {
  list-style: none;
  margin: 40px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
}
@media (max-width: 800px) { .jobs { grid-template-columns: 1fr; } }
.jobs li {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-xs);
  padding: 24px 22px;
}
.jobs .job-kicker {
  display: inline-block;
  font: 800 12px/1 var(--font-mono);
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--primary-foreground);
  background: var(--primary);
  border-radius: var(--radius-full);
  padding: 6px 10px;
  margin-bottom: 14px;
}
.jobs h3 { margin-bottom: 8px; }
.jobs p { color: var(--muted-foreground); font-size: 15px; margin-bottom: 0; }

/* Status legend. Dots are graphical (3:1 checked); labels stay in the
   default text colour so they pass AA regardless of the dot beside them. */
.status-legend { list-style: none; display: flex; gap: 16px; flex-wrap: wrap; margin: 16px 0 0; padding: 0; font-size: 13px; color: var(--muted-foreground); }
.status-legend li { display: flex; align-items: center; gap: 7px; }
.status-legend .dot { width: 9px; height: 9px; border-radius: 50%; display: inline-block; flex: 0 0 auto; }
.status-legend .dot-ok { background: var(--status-ok); }
.status-legend .dot-warn { background: var(--status-warn); }
.status-legend .dot-bad { background: var(--status-bad); }
/* For legends that explain a border treatment rather than a status value.
   The swatch shows the actual treatment, so it stays monochrome and the
   colour tokens above stay reserved for real product data. */
.status-legend .swatch { width: 20px; height: 11px; border: 1px solid var(--foreground); border-radius: 3px; display: inline-block; flex: 0 0 auto; }
.status-legend .swatch-spec { border-style: dashed; border-color: var(--muted-foreground); }

/* ----------------------------------------------------------- proof / demo */

.proof-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: 40px;
  align-items: start;
  margin-top: 30px;
}
/* minmax(0, 1fr) rather than 1fr: a bare 1fr floors the track at min-content,
   so the terminal block's longest line widens the column past the viewport
   and the whole page scrolls sideways on a phone. */
@media (max-width: 900px) { .proof-grid { grid-template-columns: minmax(0, 1fr); } }

.demo-panel {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-sm);
  padding: 20px;
}
.demo-panel .demo-label {
  font: 700 12px/1 var(--font-mono);
  text-transform: uppercase;
  letter-spacing: .06em;
  color: var(--muted-foreground);
  margin-bottom: 12px;
}
.demo-intro { font: 14px/1.5 var(--font-mono); color: var(--muted-foreground); margin-bottom: 14px; }
.demo-intro strong { color: var(--foreground); }

/* Generic three-column data rows: key, description, trailing meta. */
.spec-list { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 8px; }
.spec-list li {
  display: grid;
  grid-template-columns: minmax(64px, auto) 1fr auto;
  gap: 10px;
  align-items: baseline;
  background: var(--muted);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 10px 12px;
  font-size: 14px;
}
.spec-list .key { font: 700 14px/1.35 var(--font-mono); color: var(--foreground); }
.spec-list .name { color: var(--foreground); }
.spec-list .name .tag { color: var(--muted-foreground); font: 12px/1 var(--font-mono); margin-left: 6px; }
.spec-list .meta { color: var(--muted-foreground); font: 12px/1 var(--font-mono); text-align: right; white-space: nowrap; }
.spec-list li.is-main { background: var(--card); border-color: var(--foreground); border-width: 1.5px; }
/* Dashed = present but not yet real. Mark absence honestly, never hide it. */
.spec-list li.is-pending { border-style: dashed; background: var(--card); }
.spec-list li.is-pending .name { color: var(--muted-foreground); font-style: italic; }

@media (max-width: 480px) {
  .spec-list li { grid-template-columns: 1fr; gap: 4px; }
  .spec-list .meta { text-align: left; }
}

/* Grid rather than flex-wrap: with flex, one long label pushes a single stat
   onto its own line and the row reads as 1-then-2 instead of an even set. */
.stat-row { display: grid; grid-template-columns: repeat(auto-fit, minmax(148px, 1fr)); gap: 22px; margin: 22px 0; }
.stat b { display: block; font: 800 26px/1.1 var(--font-mono); color: var(--foreground); }
.stat span { font-size: 13px; color: var(--muted-foreground); }

/* --------------------------------------------------------------- terminal */

.terminal {
  position: relative;
  background: var(--foreground);
  color: #fafafa;
  border-radius: var(--radius-xl);
  padding: 18px 20px;
  font: 13.5px/1.7 var(--font-mono);
  margin: 22px 0;
}
.terminal .prompt { color: #a3a3a3; user-select: none; }
.terminal .comment { color: #a3a3a3; }
.terminal pre { margin: 0; font: inherit; overflow-x: auto; }
.terminal:has(.copy-button) pre { padding-right: 84px; }

.copy-button {
  position: absolute;
  top: 12px;
  right: 12px;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 10px;
  border: 1px solid #404040;
  border-radius: var(--radius-sm);
  background: #1c1c1c;
  color: #d4d4d4;
  font: 650 12px/1 var(--font-sans);
  cursor: pointer;
  transition: background-color 120ms ease, color 120ms ease, border-color 120ms ease;
}
.copy-button:hover { background: #2e2e2e; color: #fafafa; border-color: #6b6b6b; }
.copy-button[data-copied="true"] { background: #fafafa; color: #0a0a0a; border-color: #fafafa; }
.copy-icon { flex: none; display: block; }

@media (prefers-reduced-motion: reduce) {
  .copy-button { transition: none; }
}

/* --------------------------------------------------------------- figures */

.figure { margin: 26px 0; display: flex; flex-direction: column; gap: 12px; }
.diagram {
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  background: var(--card);
  padding: 22px 20px;
}
.diagram svg { display: block; width: 100%; height: auto; }
.figure figcaption { color: var(--muted-foreground); font-size: 13px; line-height: 1.65; }

/* A diagram scaled to a phone shrinks its labels below legibility. Give it a
   floor and let the container scroll instead of shrinking the text. */
@media (max-width: 620px) {
  .diagram { overflow-x: auto; }
  .diagram svg { min-width: 460px; }
}
.callout-n {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--foreground);
  color: var(--background);
  font-size: 11px;
  font-weight: 700;
  margin-right: 3px;
}

/* ------------------------------------------------------------- comparison */

.compare-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; margin-top: 34px; }
@media (max-width: 760px) { .compare-grid { grid-template-columns: 1fr; } }
.compare-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-xs);
  padding: 22px;
}
.compare-card h3 { color: var(--muted-foreground); font-size: 14px; text-transform: uppercase; letter-spacing: .05em; margin-bottom: 12px; }
.compare-card p { font-size: 15px; margin-bottom: 0; }
.compare-close { margin-top: 26px; font-size: 17px; }
.compare-close strong { color: var(--foreground); }

/* ------------------------------------------------------------- data table */

.data-table { width: 100%; border-collapse: collapse; margin-top: 26px; font-size: 15px; }
.data-table caption { text-align: left; color: var(--muted-foreground); font-size: 14px; margin-bottom: 10px; }
.data-table th, .data-table td { text-align: left; padding: 12px 14px; border-bottom: 1px solid var(--border); vertical-align: top; }
.data-table thead th {
  font: 800 12px/1 var(--font-mono);
  text-transform: uppercase;
  letter-spacing: .06em;
  color: var(--muted-foreground);
  border-bottom: 1.5px solid var(--foreground);
}
.data-table tbody tr:last-child td { border-bottom: none; }
.data-table code { font: 13px/1.5 var(--font-mono); background: var(--muted); border-radius: var(--radius-sm); padding: 2px 6px; }

@media (max-width: 640px) {
  .data-table, .data-table thead, .data-table tbody, .data-table tr, .data-table th, .data-table td { display: block; }
  .data-table thead { display: none; }
  .data-table tr { border: 1px solid var(--border); border-radius: var(--radius-md); margin-bottom: 12px; padding: 6px 4px; }
  .data-table td { border-bottom: none; padding: 8px 12px; }
}

/* ------------------------------------------------------------- assurances */

.assurance-list { list-style: none; margin: 26px 0 0; padding: 0; display: grid; grid-template-columns: repeat(2, 1fr); gap: 14px; }
@media (max-width: 640px) { .assurance-list { grid-template-columns: 1fr; } }
.assurance-list li {
  display: flex;
  gap: 12px;
  align-items: flex-start;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-xs);
  padding: 14px 16px;
  font-size: 14.5px;
}
.assurance-list .icon { flex: 0 0 auto; color: var(--foreground); margin-top: 2px; }

/* -------------------------------------------------------------------- faq */

.faq-list { margin-top: 30px; display: flex; flex-direction: column; gap: 10px; }
.faq-item {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-xs);
  overflow: hidden;
}
.faq-item summary {
  cursor: pointer;
  padding: 16px 18px;
  font-weight: 650;
  font-size: 16px;
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary .chevron { flex: 0 0 auto; transition: transform .15s ease; color: var(--muted-foreground); }
.faq-item[open] summary .chevron { transform: rotate(90deg); }
.faq-item summary:hover { background: var(--muted); }
.faq-item .faq-answer { padding: 0 18px 18px; color: var(--muted-foreground); font-size: 15px; max-width: 72ch; }
.faq-item .faq-answer p { margin-bottom: 0; }
.faq-item .faq-answer p + p { margin-top: .8em; }

/* ----------------------------------------------------------------- footer */

.site-footer { padding: 40px 0 60px; }
.site-footer .container { display: flex; flex-direction: column; gap: 14px; }
.footer-links { display: flex; align-items: center; gap: 16px; flex-wrap: wrap; }
.footer-links a { color: var(--foreground); font-weight: 650; text-decoration: none; }
.footer-links a:hover { text-decoration: underline; text-underline-offset: 3px; }
.footer-credits { color: var(--muted-foreground); font-size: 13px; max-width: 80ch; }
.footer-credits a { color: var(--muted-foreground); text-decoration-color: var(--border); }
.footer-credits a:hover { color: var(--foreground); text-decoration-color: currentColor; }
.footer-note { color: var(--muted-foreground); font-size: 12.5px; }

.footer-author {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 12px;
  margin-top: 10px;
  padding-top: 20px;
  border-top: 1px solid var(--border);
}
.footer-bio { color: var(--muted-foreground); font-size: 13px; max-width: 62ch; margin: 0 auto; }
.connect-links { display: flex; align-items: center; justify-content: center; gap: 10px; flex-wrap: wrap; }
.connect-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 14px;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  color: var(--foreground);
  font-size: 13.5px;
  font-weight: 650;
  text-decoration: none;
  background: transparent;
  transition: background-color 120ms ease, border-color 120ms ease, color 120ms ease;
}
.connect-link:hover {
  background: var(--foreground);
  border-color: var(--foreground);
  color: var(--background);
}
.connect-icon { flex: none; display: block; }

@media (prefers-reduced-motion: reduce) {
  .connect-link { transition: none; }
}

/* ------------------------------------------------------------- misc utils */

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