/* ============================================================
   Lexicon Community — refined editorial reference
   Typography: Source Serif 4 (display + prose) + Public Sans
   (UI + labels) + system mono (identifiers only).
   Colors: OKLCH neutrals tinted toward brand green; single
   accent used sparingly. No glassmorphism, gradient text, or
   border-left stripes.
   ============================================================ */

/* ---------- Tokens ---------- */
:root {
  /* 4pt spacing scale */
  --space-2xs: 0.25rem; /* 4  */
  --space-xs:  0.5rem;  /* 8  */
  --space-sm:  0.75rem; /* 12 */
  --space-md:  1rem;    /* 16 */
  --space-lg:  1.5rem;  /* 24 */
  --space-xl:  2rem;    /* 32 */
  --space-2xl: 3rem;    /* 48 */
  --space-3xl: 4rem;    /* 64 */
  --space-4xl: 6rem;    /* 96 */

  /* Paper neutrals — off-white warmed and tinted toward brand green */
  --bg:                oklch(0.985 0.005 135);
  --bg-alt:            oklch(0.955 0.006 135);
  --surface:           oklch(0.995 0.003 135);
  --ink:               oklch(0.22  0.02  150);
  --ink-soft:          oklch(0.38  0.02  150);
  --muted:             oklch(0.55  0.012 145);
  --hairline:          oklch(0.91  0.01  135);
  --hairline-strong:   oklch(0.82  0.012 135);

  /* Single accent, used sparingly */
  --accent:            oklch(0.55  0.14  150);
  --accent-ink:        oklch(0.42  0.12  152);
  --accent-wash:       oklch(0.95  0.03  148);

  /* Typography */
  --font-serif: "Source Serif 4", "Iowan Old Style", "Palatino Linotype",
    Georgia, serif;
  --font-sans: "Public Sans", -apple-system, BlinkMacSystemFont,
    "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, "SF Mono", Menlo, Consolas, monospace;

  --radius-xs: 2px;
  --radius-sm: 4px;
  --radius-md: 6px;

  --container: 68rem;
  --measure:   42rem; /* reading width cap */
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg:              oklch(0.175 0.008 150);
    --bg-alt:          oklch(0.21  0.01  150);
    --surface:         oklch(0.23  0.012 150);
    --ink:             oklch(0.94  0.01  125);
    --ink-soft:        oklch(0.80  0.013 135);
    --muted:           oklch(0.62  0.012 145);
    --hairline:        oklch(0.30  0.014 150);
    --hairline-strong: oklch(0.40  0.016 150);

    --accent:          oklch(0.78  0.14  148);
    --accent-ink:      oklch(0.86  0.12  148);
    --accent-wash:     oklch(0.27  0.04  148);
  }
}

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font-serif);
  font-size: 1.0625rem; /* 17px */
  line-height: 1.65;
  color: var(--ink);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  font-feature-settings: "kern" 1, "liga" 1;
}

@media (prefers-color-scheme: dark) {
  body {
    line-height: 1.72;
  }
}

/* ---------- Type scale ---------- */
h1,
h2 {
  font-family: var(--font-serif);
  color: var(--ink);
  margin: 0 0 var(--space-sm);
  letter-spacing: -0.018em;
  line-height: 1.12;
  font-weight: 600;
  font-feature-settings: "kern" 1, "liga" 1, "onum" 1; /* old-style numerals in headings */
}

h3,
h4 {
  font-family: var(--font-sans);
  color: var(--ink);
  margin: 0 0 var(--space-xs);
  letter-spacing: -0.005em;
  line-height: 1.3;
}

h1 {
  font-size: clamp(2.25rem, 2rem + 1.8vw, 3.25rem); /* 36→52 */
  letter-spacing: -0.024em;
}

h2 {
  font-size: clamp(1.625rem, 1.4rem + 1vw, 2rem); /* 26→32 */
}

h3 {
  font-size: 1.0625rem; /* 17px */
  font-weight: 600;
}

h4 {
  font-size: 1rem;
  font-weight: 500;
}

p {
  margin: 0 0 var(--space-md);
  color: var(--ink-soft);
  max-width: var(--measure);
}

a {
  color: var(--accent-ink);
  text-decoration-color: color-mix(
    in oklab,
    var(--accent) 45%,
    transparent
  );
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
  transition: color 120ms ease, text-decoration-color 120ms ease;
}
a:hover {
  color: var(--accent);
  text-decoration-color: currentColor;
}

code {
  font-family: var(--font-mono);
  font-size: 0.85em;
  color: var(--ink);
  background: var(--bg-alt);
  padding: 0.08em 0.35em;
  border-radius: var(--radius-xs);
  border: 1px solid var(--hairline);
}

ul,
ol,
dl {
  margin: 0;
  padding: 0;
}

hr {
  border: none;
  border-top: 1px solid var(--hairline);
  margin: var(--space-xl) 0;
}

/* ---------- Layout ---------- */
.container {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  padding: var(--space-xs) var(--space-sm);
  background: var(--ink);
  color: var(--bg);
  font-family: var(--font-sans);
  font-size: 0.875rem;
  border-radius: var(--radius-sm);
  z-index: 100;
}
.skip-link:focus {
  left: 16px;
  top: 16px;
}

/* ---------- Header ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: var(--bg);
  border-bottom: 1px solid var(--hairline);
  font-family: var(--font-sans);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
  gap: var(--space-lg);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  color: var(--ink);
  text-decoration: none;
  font-size: 0.9375rem;
  font-weight: 500;
  letter-spacing: -0.005em;
}
.brand:hover {
  color: var(--accent-ink);
}

.nav-list {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
  list-style: none;
  font-size: 0.9375rem;
}

.nav-list a {
  color: var(--ink-soft);
  text-decoration: none;
  font-weight: 400;
}
.nav-list a:hover {
  color: var(--accent-ink);
}
.nav-external {
  color: var(--ink) !important;
  font-weight: 500;
}

@media (max-width: 640px) {
  .nav-list li:not(:last-child) {
    display: none;
  }
}

/* ---------- Hero ---------- */
.hero {
  padding: clamp(4rem, 5rem + 4vw, 8rem) 0 clamp(3rem, 3rem + 4vw, 6rem);
  border-bottom: 1px solid var(--hairline);
}

.hero .container {
  max-width: 48rem;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  margin: 0 0 var(--space-lg);
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--accent-ink);
  max-width: none;
}

.eyebrow::before {
  content: "";
  display: inline-block;
  width: 32px;
  height: 2px;
  background: var(--accent);
  flex: none;
}

.hero h1 {
  max-width: 18ch;
  margin: 0 0 var(--space-lg);
}

.accent {
  color: var(--ink);
  background: none;
  padding: 0;
  text-decoration: underline;
  text-decoration-color: var(--accent);
  text-decoration-thickness: 0.08em;
  text-underline-offset: 0.14em;
  text-decoration-skip-ink: none;
}

.lede {
  font-family: var(--font-serif);
  font-size: clamp(1.125rem, 1rem + 0.4vw, 1.25rem);
  line-height: 1.55;
  color: var(--ink);
  max-width: 38rem;
  margin: 0 0 var(--space-xl);
}

.cta-row {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
  margin-top: var(--space-sm);
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  padding: 0.625rem 1rem;
  font-family: var(--font-sans);
  font-size: 0.9375rem;
  font-weight: 500;
  letter-spacing: -0.005em;
  border-radius: var(--radius-sm);
  text-decoration: none;
  border: 1px solid transparent;
  cursor: pointer;
  transition: background-color 120ms ease, color 120ms ease,
    border-color 120ms ease;
}

.btn-primary {
  background: var(--ink);
  color: var(--bg);
}
.btn-primary:hover {
  background: var(--accent-ink);
  color: var(--bg);
}

.btn-ghost {
  background: transparent;
  color: var(--ink);
  border-color: var(--hairline-strong);
}
.btn-ghost:hover {
  background: var(--surface);
  border-color: var(--accent-ink);
  color: var(--accent-ink);
}

/* ---------- Sections ---------- */
.section {
  padding: clamp(4rem, 3rem + 5vw, 7rem) 0;
  border-bottom: 1px solid var(--hairline);
}

.section-alt {
  background: var(--bg-alt);
}

.two-col {
  display: grid;
  grid-template-columns: minmax(0, 13rem) minmax(0, 1fr);
  gap: clamp(2rem, 1.5rem + 4vw, 5rem);
  align-items: start;
}

@media (max-width: 820px) {
  .two-col {
    grid-template-columns: 1fr;
    gap: var(--space-lg);
  }
}

.section-head {
  position: sticky;
  top: 6rem;
}

@media (max-width: 820px) {
  .section-head {
    position: static;
  }
}

.section-head h2 {
  margin-top: var(--space-2xs);
}

.section-head-wide {
  position: static;
  max-width: 44rem;
  margin-bottom: var(--space-2xl);
}

.section-label {
  display: block;
  font-family: var(--font-sans);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--muted);
  margin: 0 0 var(--space-sm);
  font-weight: 500;
}

.section-desc {
  font-family: var(--font-serif);
  font-size: 1.0625rem;
  color: var(--ink-soft);
  max-width: 44rem;
  line-height: 1.6;
}

.prose-lead {
  font-family: var(--font-serif);
  font-size: 1.125rem;
  color: var(--ink);
  line-height: 1.55;
  margin: 0 0 var(--space-lg);
  max-width: var(--measure);
}

/* ---------- Definition lists (the reference backbone) ---------- */
.defs {
  display: grid;
  grid-template-columns: minmax(7rem, 12rem) minmax(0, 1fr);
  column-gap: clamp(1.5rem, 1rem + 2vw, 2.5rem);
  row-gap: var(--space-lg);
  margin: var(--space-lg) 0 var(--space-2xl);
  padding: var(--space-lg) 0;
  border-top: 1px solid var(--hairline);
  border-bottom: 1px solid var(--hairline);
}

.defs dt {
  font-family: var(--font-sans);
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--ink);
  padding-top: 0.1em;
}

.defs dd {
  margin: 0;
  font-family: var(--font-serif);
  font-size: 1rem;
  line-height: 1.55;
  color: var(--ink-soft);
  max-width: 38rem;
}

@media (max-width: 640px) {
  .defs {
    grid-template-columns: 1fr;
    row-gap: var(--space-xs);
  }
  .defs dt {
    padding-top: var(--space-sm);
  }
  .defs dt:first-of-type {
    padding-top: 0;
  }
}

/* ---------- Mini label (small-caps sans) ---------- */
.mini-label {
  font-family: var(--font-sans);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--muted);
  font-weight: 500;
  margin: 0 0 var(--space-sm);
  display: block;
}

/* ---------- TSC roster ---------- */
.tsc {
  margin-top: var(--space-2xl);
}

.tsc > .mini-label {
  margin-bottom: var(--space-md);
}

.roster {
  display: grid;
  grid-template-columns: minmax(0, auto) minmax(0, 1fr);
  column-gap: var(--space-lg);
  row-gap: var(--space-xs);
}

.roster dt {
  font-family: var(--font-sans);
  font-size: 0.9375rem;
  color: var(--ink);
  font-weight: 500;
}

.roster dd {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--muted);
  padding-top: 0.15em;
}

.roster dd a {
  color: inherit;
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 120ms ease, border-color 120ms ease;
}
.roster dd a:hover {
  color: var(--accent-ink);
  border-bottom-color: var(--accent);
}

/* ---------- Schemas ---------- */
.schema-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(17rem, 1fr));
  gap: var(--space-md);
}

.schema-card {
  display: flex;
  flex-direction: column;
  background: var(--surface);
  border: 1px solid var(--hairline);
  border-radius: var(--radius-md);
  padding: var(--space-lg);
  transition: border-color 150ms ease;
}

.schema-card:hover {
  border-color: var(--accent-ink);
}

.schema-card header {
  margin-bottom: var(--space-sm);
}

.schema-card h3 {
  font-family: var(--font-sans);
  font-size: 1.0625rem;
  font-weight: 600;
  margin: 0 0 var(--space-2xs);
  color: var(--ink);
}

.nsid {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--accent-ink);
  background: transparent;
  border: none;
  padding: 0;
  letter-spacing: 0;
}

.schema-card > p {
  font-family: var(--font-serif);
  font-size: 0.9375rem;
  line-height: 1.55;
  color: var(--ink-soft);
  margin: 0 0 var(--space-md);
  max-width: none;
}

.record-list {
  list-style: none;
  margin: 0 0 var(--space-md);
  padding: var(--space-sm) 0;
  border-top: 1px solid var(--hairline);
  border-bottom: 1px solid var(--hairline);
  display: grid;
  gap: var(--space-2xs);
}

.record-list li {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-sm);
  font-family: var(--font-mono);
  font-size: 0.8125rem;
}

.record-list code {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--ink);
  background: transparent;
  border: none;
  padding: 0;
}

.rec-type {
  font-family: var(--font-sans);
  font-size: 0.6875rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--muted);
  font-weight: 500;
}

.schema-card footer {
  margin-top: auto;
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-md);
  font-family: var(--font-sans);
  font-size: 0.875rem;
}

.schema-card footer a {
  color: var(--ink-soft);
  text-decoration: none;
  border-bottom: 1px solid var(--hairline-strong);
  padding-bottom: 1px;
}
.schema-card footer a:hover {
  color: var(--accent-ink);
  border-bottom-color: var(--accent);
}

.schema-card-cta {
  background: transparent;
  border-style: dashed;
  border-color: var(--hairline-strong);
}
.schema-card-cta:hover {
  border-color: var(--accent-ink);
}
.schema-card-cta h3 {
  color: var(--muted);
  font-style: italic;
  font-family: var(--font-serif);
  font-weight: 500;
}
.schema-card-cta .nsid {
  color: var(--muted);
}

/* ---------- Grid note (colophon below schemas) ---------- */
/* ---------- Steps ---------- */
.steps {
  list-style: none;
  margin: var(--space-lg) 0 var(--space-2xl);
  padding: 0;
  display: grid;
  gap: 0;
}

.steps li {
  display: grid;
  grid-template-columns: 2.25rem 1fr;
  gap: var(--space-md);
  padding: var(--space-md) 0;
  border-top: 1px solid var(--hairline);
}
.steps li:first-child {
  border-top: none;
  padding-top: 0;
}
.steps li:last-child {
  padding-bottom: 0;
}

.step-num {
  font-family: var(--font-sans);
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--muted);
  font-variant-numeric: tabular-nums;
  padding-top: 0.32em;
  letter-spacing: 0.04em;
}

.step-body h3 {
  font-family: var(--font-sans);
  font-size: 1.0625rem;
  font-weight: 600;
  margin: 0 0 var(--space-xs);
  color: var(--ink);
}

.step-body p {
  margin: 0;
  font-family: var(--font-serif);
  font-size: 1rem;
  line-height: 1.6;
  color: var(--ink-soft);
  max-width: 42rem;
}

/* ---------- Link index ---------- */
.link-index {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(18rem, 1fr));
  column-gap: clamp(1.5rem, 1rem + 3vw, 3rem);
  row-gap: var(--space-md);
  margin: var(--space-md) 0 0;
  padding-top: var(--space-md);
  border-top: 1px solid var(--hairline);
}

.link-index dt {
  font-family: var(--font-sans);
  font-size: 1rem;
  font-weight: 500;
  margin: 0 0 var(--space-2xs);
}

.link-index dt a {
  color: var(--ink);
  text-decoration: none;
  border-bottom: 1px solid var(--hairline-strong);
  padding-bottom: 2px;
}
.link-index dt a:hover {
  color: var(--accent-ink);
  border-bottom-color: var(--accent);
}

.link-index dd {
  margin: 0 0 var(--space-sm);
  font-family: var(--font-serif);
  font-size: 0.9375rem;
  color: var(--ink-soft);
  max-width: 34rem;
}

/* ---------- Footer ---------- */
.site-footer {
  border-top: 1px solid var(--hairline);
  background: var(--bg-alt);
  padding: var(--space-xl) 0;
  font-family: var(--font-sans);
}

.footer-inner {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-md) var(--space-xl);
  align-items: center;
  justify-content: space-between;
}

.footer-brand {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--ink);
}

.footer-meta {
  margin: 0;
  font-size: 0.8125rem;
  color: var(--muted);
  max-width: 52ch;
  line-height: 1.55;
}

.footer-links {
  display: flex;
  gap: var(--space-md);
  list-style: none;
  font-size: 0.875rem;
}

.footer-links a {
  color: var(--ink-soft);
  text-decoration: none;
}
.footer-links a:hover {
  color: var(--accent-ink);
}

/* ---------- Focus ---------- */
:focus-visible {
  outline: 2px solid var(--accent-ink);
  outline-offset: 3px;
  border-radius: var(--radius-xs);
}

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