/* =============================================================================
   ADU Explorer — Base styles
   Reset · typography · primitives · navigation · footer
   ============================================================================= */

/* -----------------------------------------------------------------------------
   Modern, minimal reset
   ----------------------------------------------------------------------------- */
*, *::before, *::after { box-sizing: border-box; }
* { margin: 0; }

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

body {
  min-height: 100dvh;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-serif);
  font-size: var(--t-body);
  line-height: var(--lh-body);
  font-feature-settings: "kern", "liga", "calt";
  font-variation-settings: "opsz" 14, "SOFT" 30;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  /* Subtle paper texture — a tiny SVG noise pattern, repeated. */
  background-image:
    url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='160' height='160'><filter id='n'><feTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='2' stitchTiles='stitch'/><feColorMatrix values='0 0 0 0 0.1  0 0 0 0 0.09  0 0 0 0 0.07  0 0 0 0.045 0'/></filter><rect width='100%25' height='100%25' filter='url(%23n)'/></svg>");
  background-size: 160px 160px;
}

img, picture, svg, video { display: block; max-width: 100%; }

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

a {
  color: var(--ink);
  text-decoration: underline;
  text-decoration-color: var(--rule);
  text-decoration-thickness: 1px;
  text-underline-offset: 0.22em;
  transition: text-decoration-color var(--t-fast) var(--ease),
              color var(--t-fast) var(--ease);
}
a:hover { text-decoration-color: var(--stamp); color: var(--stamp); }
a:focus-visible {
  outline: 2px solid var(--topo);
  outline-offset: 3px;
  border-radius: 1px;
}

::selection { background: var(--highlight); color: var(--ink); }

/* -----------------------------------------------------------------------------
   Typography primitives
   ----------------------------------------------------------------------------- */
.display {
  font-family: var(--font-serif);
  font-weight: 400;
  font-size: var(--t-display);
  line-height: var(--lh-display);
  letter-spacing: -0.025em;
  font-variation-settings: "opsz" 96, "SOFT" 0, "wght" 380;
  text-wrap: balance;
}
@media (min-width: 64rem) {
  .display { font-size: var(--t-display-lg); }
}

.h1 {
  font-family: var(--font-serif);
  font-size: var(--t-h1);
  line-height: var(--lh-tight);
  letter-spacing: -0.018em;
  font-variation-settings: "opsz" 72, "wght" 420;
  text-wrap: balance;
}

.h2 {
  font-family: var(--font-serif);
  font-size: var(--t-h2);
  line-height: var(--lh-snug);
  letter-spacing: -0.012em;
  font-variation-settings: "opsz" 36, "wght" 440;
  text-wrap: balance;
}

.h3 {
  font-family: var(--font-serif);
  font-size: var(--t-h3);
  line-height: var(--lh-snug);
  letter-spacing: -0.006em;
  font-variation-settings: "opsz" 28, "wght" 460;
  text-wrap: balance;
}

.lede {
  font-family: var(--font-serif);
  font-size: var(--t-lede);
  line-height: var(--lh-prose);
  font-variation-settings: "opsz" 24, "wght" 380;
  color: var(--ink);
  max-width: 38ch;
  text-wrap: pretty;
}

.prose {
  font-size: var(--t-body);
  line-height: var(--lh-prose);
  max-width: var(--max-prose);
  text-wrap: pretty;
}
.prose p + p { margin-top: var(--s-2); }

/* Eyebrow — mono small caps label */
.eyebrow {
  font-family: var(--font-mono);
  font-size: var(--t-mono-sm);
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--ink-soft);
  font-weight: 500;
}
.eyebrow--stamp { color: var(--stamp); }
.eyebrow--topo  { color: var(--topo); }

/* Mono utility — for coordinates, sheet stamps */
.mono {
  font-family: var(--font-mono);
  font-feature-settings: "tnum" on, "zero" on;
}
.mono-xs  { font-family: var(--font-mono); font-size: var(--t-mono-xs); }
.mono-sm  { font-family: var(--font-mono); font-size: var(--t-mono-sm); }
.mono-md  { font-family: var(--font-mono); font-size: var(--t-mono-md); }

/* -----------------------------------------------------------------------------
   Layout primitives
   ----------------------------------------------------------------------------- */
.page {
  max-width: var(--max-page);
  margin-inline: auto;
  padding-inline: var(--gutter);
}
@media (min-width: 48rem) { .page { padding-inline: var(--gutter-lg); } }

.rule    { border: 0; border-top: var(--rule-w) solid var(--rule); margin: 0; }
.rule-bold { border: 0; border-top: 2px solid var(--ink); margin: 0; }

/* -----------------------------------------------------------------------------
   Buttons
   ----------------------------------------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--s-1);
  font-family: var(--font-mono);
  font-size: var(--t-mono-md);
  font-weight: 500;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  text-decoration: none;
  padding: 0.875rem 1.5rem;
  border: 1px solid var(--ink);
  background: var(--ink);
  color: var(--paper);
  min-height: 48px;
  cursor: pointer;
  transition: background var(--t-fast) var(--ease),
              color var(--t-fast) var(--ease),
              border-color var(--t-fast) var(--ease),
              transform var(--t-fast) var(--ease);
}
.btn:hover { background: var(--stamp); border-color: var(--stamp); color: var(--paper); }
.btn:active { transform: translateY(1px); }

.btn--ghost {
  background: transparent;
  color: var(--ink);
}
.btn--ghost:hover {
  background: var(--ink);
  color: var(--paper);
}

.btn--stamp {
  background: var(--stamp);
  border-color: var(--stamp);
}
.btn--stamp:hover {
  background: var(--ink);
  border-color: var(--ink);
}

/* -----------------------------------------------------------------------------
   Sheet header — tiny print at the very top of the page
   ----------------------------------------------------------------------------- */
.sheet-header {
  border-bottom: var(--rule-w) solid var(--rule);
  background: var(--paper);
}
.sheet-header__inner {
  max-width: var(--max-page);
  margin-inline: auto;
  padding: var(--s-1) var(--gutter);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--s-2);
  font-family: var(--font-mono);
  font-size: var(--t-mono-xs);
  color: var(--ink-soft);
  letter-spacing: 0.1em;
  text-transform: uppercase;
}
.sheet-header__coords { color: var(--topo); }
.sheet-header__date  { white-space: nowrap; }
@media (max-width: 36rem) {
  .sheet-header__date { display: none; }
}

/* -----------------------------------------------------------------------------
   Nav
   ----------------------------------------------------------------------------- */
.nav {
  border-bottom: var(--rule-w) solid var(--rule);
  background: var(--paper);
  position: sticky;
  top: 0;
  z-index: 50;
  backdrop-filter: blur(8px);
}
.nav__inner {
  max-width: var(--max-page);
  margin-inline: auto;
  padding: var(--s-2) var(--gutter);
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--s-3);
}
.nav__brand {
  font-family: var(--font-serif);
  font-variation-settings: "opsz" 36, "wght" 480;
  font-size: 1.375rem;
  letter-spacing: -0.005em;
  color: var(--ink);
  text-decoration: none;
}
.nav__brand-mark { color: var(--stamp); }
.nav__list {
  display: flex;
  gap: var(--s-4);
  list-style: none;
  padding: 0;
}
.nav__list a {
  font-family: var(--font-mono);
  font-size: var(--t-mono-sm);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-soft);
  text-decoration: none;
}
.nav__list a:hover { color: var(--stamp); }
.nav__list a[aria-current="page"] {
  color: var(--ink);
  border-bottom: 2px solid var(--stamp);
  padding-bottom: 2px;
}
@media (max-width: 48rem) {
  .nav__list { gap: var(--s-2); }
  .nav__list li:nth-child(n+4) { display: none; }
}

/* -----------------------------------------------------------------------------
   Section scaffold — the load-bearing dossier element.
   Every major section uses .section + .section__margin + .section__body.
   ----------------------------------------------------------------------------- */
.section {
  position: relative;
  padding-block: var(--s-6);
  border-top: var(--rule-w) solid var(--rule);
}
.section:first-of-type { border-top: 0; padding-top: var(--s-5); }
.section:last-of-type  { border-bottom: var(--rule-w) solid var(--rule); }

.section__grid {
  max-width: var(--max-page);
  margin-inline: auto;
  padding-inline: var(--gutter);
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--s-4);
}
@media (min-width: 64rem) {
  .section__grid {
    grid-template-columns: 7rem 1fr;
    column-gap: var(--s-5);
    padding-inline: var(--gutter-lg);
  }
}

.section__margin {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: var(--s-3);
}
@media (min-width: 64rem) {
  .section__margin {
    flex-direction: column;
    align-items: stretch;
    position: sticky;
    top: 4rem;
    align-self: start;
  }
}

.section__numeral {
  font-family: var(--font-serif);
  font-size: var(--t-numeral);
  line-height: 1;
  font-variation-settings: "opsz" 72, "wght" 360;
  color: var(--stamp);
  letter-spacing: -0.02em;
  display: block;
}

.section__stamp {
  font-family: var(--font-mono);
  font-size: var(--t-mono-xs);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--ink-soft);
  display: block;
  margin-top: var(--s-1);
}
.section__stamp .sheet-num {
  color: var(--stamp);
  font-weight: 600;
}

.section__body {
  min-width: 0;
}

.section__title {
  font-family: var(--font-serif);
  font-size: var(--t-h1);
  line-height: var(--lh-tight);
  letter-spacing: -0.014em;
  font-variation-settings: "opsz" 56, "wght" 420;
  text-wrap: balance;
  margin-bottom: var(--s-3);
}
@media (min-width: 64rem) {
  .section__title { font-size: 3.5rem; }
}

.section__lede {
  font-size: var(--t-body-lg);
  line-height: var(--lh-prose);
  max-width: 50ch;
  color: var(--ink);
  margin-bottom: var(--s-4);
  font-variation-settings: "opsz" 20, "wght" 380;
}

/* -----------------------------------------------------------------------------
   Registration mark — used decoratively at section corners
   ----------------------------------------------------------------------------- */
.reg-mark {
  width: 14px;
  height: 14px;
  display: inline-block;
  color: var(--rule-strong);
}
.reg-mark svg { width: 100%; height: 100%; }

/* -----------------------------------------------------------------------------
   Coordinate strip — small mono lines beneath city names
   ----------------------------------------------------------------------------- */
.coords {
  font-family: var(--font-mono);
  font-size: var(--t-mono-sm);
  letter-spacing: 0.04em;
  color: var(--topo);
  display: inline-flex;
  align-items: center;
  gap: 0.4em;
}
.coords::before {
  content: "⊕";
  color: var(--topo);
  font-size: 0.95em;
}

/* -----------------------------------------------------------------------------
   Footer / colophon
   ----------------------------------------------------------------------------- */
.colophon {
  border-top: 2px solid var(--ink);
  background: var(--paper);
  padding-block: var(--s-6) var(--s-4);
  margin-top: var(--s-6);
}
.colophon__inner {
  max-width: var(--max-page);
  margin-inline: auto;
  padding-inline: var(--gutter);
  display: grid;
  gap: var(--s-4);
  grid-template-columns: 1fr;
}
@media (min-width: 48rem) {
  .colophon__inner {
    grid-template-columns: 2fr 1fr 1fr;
    padding-inline: var(--gutter-lg);
  }
}

.colophon__brand {
  font-family: var(--font-serif);
  font-size: 1.5rem;
  font-variation-settings: "opsz" 36, "wght" 460;
  margin-bottom: var(--s-1);
}
.colophon__brand-mark { color: var(--stamp); }

.colophon__tagline {
  font-size: var(--t-body-sm);
  color: var(--ink-soft);
  max-width: 32ch;
}

.colophon__h {
  font-family: var(--font-mono);
  font-size: var(--t-mono-sm);
  text-transform: uppercase;
  letter-spacing: 0.14em;
  color: var(--ink-soft);
  margin-bottom: var(--s-2);
}

.colophon__list {
  list-style: none;
  padding: 0;
  display: grid;
  gap: var(--s-1);
}
.colophon__list a {
  font-size: var(--t-body-sm);
  text-decoration: none;
  color: var(--ink);
  border-bottom: 1px solid transparent;
}
.colophon__list a:hover {
  border-bottom-color: var(--stamp);
  color: var(--stamp);
}

.colophon__legal {
  max-width: var(--max-page);
  margin: var(--s-4) auto 0;
  padding: var(--s-3) var(--gutter) 0;
  border-top: var(--rule-w) solid var(--rule);
  font-family: var(--font-mono);
  font-size: var(--t-mono-xs);
  color: var(--ink-faded);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--s-2);
}
@media (min-width: 48rem) {
  .colophon__legal { padding-inline: var(--gutter-lg); }
}

/* -----------------------------------------------------------------------------
   Skip link (a11y)
   ----------------------------------------------------------------------------- */
.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--ink);
  color: var(--paper);
  padding: var(--s-1) var(--s-2);
  font-family: var(--font-mono);
  font-size: var(--t-mono-sm);
  z-index: 100;
}
.skip-link:focus { left: var(--s-2); top: var(--s-1); }

/* -----------------------------------------------------------------------------
   Utility
   ----------------------------------------------------------------------------- */
.visually-hidden {
  position: absolute !important;
  width: 1px !important; height: 1px !important;
  padding: 0 !important; margin: -1px !important;
  overflow: hidden !important;
  clip: rect(0,0,0,0) !important;
  white-space: nowrap !important;
  border: 0 !important;
}

.cluster { display: flex; flex-wrap: wrap; gap: var(--s-2); align-items: center; }
.stack > * + * { margin-top: var(--s-2); }
.stack-lg > * + * { margin-top: var(--s-3); }