/* ==========================================================================
   INSTRUMENT GRADE — BASE
   Reset, typography, layout primitives. Loads after tokens.css.
   ========================================================================== */

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

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

body {
  margin: 0;
  background: var(--gt-abyssal);
  color: var(--gt-bone);
  font-family: var(--gt-font-body);
  font-size: var(--gt-text-base);
  line-height: var(--gt-leading-normal);
  font-weight: 400;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  font-variant-numeric: tabular-nums;
}

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

::selection { background: var(--gt-solar); color: var(--gt-abyssal); }

/* --- Headings -------------------------------------------------------------
   Archivo at wdth 125. font-stretch is the correct property for a variable
   width axis; font-variation-settings is the fallback for older engines.
-------------------------------------------------------------------------- */

h1, h2, h3, h4, .gt-display {
  font-family: var(--gt-font-display);
  font-stretch: 125%;
  font-variation-settings: "wdth" 125;
  letter-spacing: var(--gt-tracking-display);
  line-height: var(--gt-leading-tight);
  color: var(--gt-ink);
  margin: 0 0 var(--gt-s5);
  text-wrap: balance;
}

h1 { font-size: var(--gt-text-4xl); font-weight: 700; }
h2 { font-size: var(--gt-text-3xl); font-weight: 700; }
h3 { font-size: var(--gt-text-xl);  font-weight: 600; line-height: var(--gt-leading-snug); }
h4 { font-size: var(--gt-text-lg);  font-weight: 600; line-height: var(--gt-leading-snug); }

p { margin: 0 0 var(--gt-s5); max-width: var(--gt-measure); color: var(--gt-ink-muted); }
p:last-child { margin-bottom: 0; }

.gt-lede {
  font-size: var(--gt-text-lg);
  line-height: var(--gt-leading-loose);
  color: var(--gt-ink);
  max-width: var(--gt-measure-tight);
}

a { color: inherit; text-decoration-thickness: 1px; text-underline-offset: 0.22em; }
a:hover { text-decoration-color: var(--gt-solar); }

/* --- Mono utility classes ------------------------------------------------
   Mono is reserved for things that are measured, labelled, or indexed.
   Never for running prose.
-------------------------------------------------------------------------- */

.gt-mono {
  font-family: var(--gt-font-mono);
  font-size: var(--gt-text-xs);
  letter-spacing: var(--gt-tracking-mono);
  font-weight: 500;
}

.gt-eyebrow {
  font-family: var(--gt-font-mono);
  font-size: var(--gt-text-xs);
  letter-spacing: var(--gt-tracking-eyebrow);
  text-transform: uppercase;
  font-weight: 500;
  color: var(--gt-accent);
  display: flex;
  align-items: center;
  gap: var(--gt-s3);
  margin: 0 0 var(--gt-s5);
}

/* The eyebrow carries a tick mark, not a bullet. It reads as a scale
   graduation, which is the point. */
.gt-eyebrow::before {
  content: "";
  width: 18px;
  height: var(--gt-hairline);
  background: currentColor;
  flex: none;
}

.gt-index {
  font-family: var(--gt-font-mono);
  font-size: var(--gt-text-2xs);
  letter-spacing: var(--gt-tracking-mono);
  color: var(--gt-ink-faint);
  font-variant-numeric: tabular-nums;
}

/* --- Layout primitives --------------------------------------------------- */

.gt-container {
  width: 100%;
  max-width: var(--gt-container);
  margin-inline: auto;
  padding-inline: var(--gt-gutter);
}

.gt-container--narrow { max-width: var(--gt-container-narrow); }

.gt-section {
  background: var(--gt-ground);
  color: var(--gt-ink);
  padding-block: var(--gt-section-y);
  position: relative;
}

/* A hairline at the top of every section, inset to the gutter. Sections
   read as stacked panels on an instrument face rather than as a scroll. */
.gt-section + .gt-section::before {
  content: "";
  position: absolute;
  inset-inline: var(--gt-gutter);
  top: 0;
  height: var(--gt-hairline);
  background: var(--gt-rule);
}

.gt-grid {
  display: grid;
  gap: var(--gt-s7) var(--gt-s6);
}

.gt-grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.gt-grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.gt-grid--4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }

/* Asymmetric split: heading column holds at a third, content takes the rest. */
.gt-split {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1.85fr);
  gap: var(--gt-s7) var(--gt-s8);
  align-items: start;
}

.gt-stack > * + * { margin-top: var(--gt-s5); }
.gt-stack-lg > * + * { margin-top: var(--gt-s7); }

@media (max-width: 900px) {
  .gt-grid--3, .gt-grid--4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .gt-split { grid-template-columns: 1fr; gap: var(--gt-s6); }
}

@media (max-width: 600px) {
  .gt-grid--2, .gt-grid--3, .gt-grid--4 { grid-template-columns: 1fr; }
}

/* --- Bracket frame -------------------------------------------------------
   The signature structural device. Four registration corners instead of a
   border. Applied to anything the page is presenting as "under measurement".
-------------------------------------------------------------------------- */

.gt-bracket {
  position: relative;
  padding: var(--gt-s6);
}

.gt-bracket::before,
.gt-bracket::after {
  content: "";
  position: absolute;
  width: var(--gt-bracket-len);
  height: var(--gt-bracket-len);
  border-color: var(--gt-accent);
  border-style: solid;
  pointer-events: none;
}

.gt-bracket::before {
  top: 0; left: 0;
  border-width: var(--gt-bracket-wt) 0 0 var(--gt-bracket-wt);
}

.gt-bracket::after {
  bottom: 0; right: 0;
  border-width: 0 var(--gt-bracket-wt) var(--gt-bracket-wt) 0;
}

/* --- Accessibility floor -------------------------------------------------- */

:where(a, button, input, textarea, select, [tabindex]):focus-visible {
  outline: none;
  box-shadow: var(--gt-focus-ring);
  border-radius: var(--gt-radius);
}

.gt-skip-link {
  position: absolute;
  left: var(--gt-s4);
  top: calc(-1 * var(--gt-s10));
  z-index: var(--gt-z-menu);
  background: var(--gt-solar);
  color: var(--gt-abyssal);
  padding: var(--gt-s3) var(--gt-s5);
  font-family: var(--gt-font-mono);
  font-size: var(--gt-text-xs);
  letter-spacing: var(--gt-tracking-mono);
  text-transform: uppercase;
  text-decoration: none;
  transition: top var(--gt-dur-fast) var(--gt-ease);
}

.gt-skip-link:focus { top: var(--gt-s4); }

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

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