/* Reset, landmarks, typography roles, focus. */

*,
*::before,
*::after {
  box-sizing: border-box;
  min-width: 0; /* long model codes must not force page scroll */
}

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

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

body {
  margin: 0;
  overflow-x: hidden;
  font-family: var(--font-sans);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-ink-800);
  background: var(--color-surface);
  -webkit-font-smoothing: antialiased;
}

@media (max-width: 639px) {
  body { padding-block-end: calc(var(--mobilebar-h) + env(safe-area-inset-bottom)); }
}

h1, h2, h3, h4, h5, h6 { margin: 0; font-weight: 700; color: var(--color-ink-800); }
h1 { font-size: clamp(28px, 7.5vw, 54px); line-height: var(--leading-tight); letter-spacing: var(--tracking-display); }
h2 { font-size: clamp(26px, 4vw, 33px); line-height: 1.15; letter-spacing: -0.01em; }
h3 { font-size: clamp(19px, 2.2vw, 21px); line-height: 1.25; }
h4 { font-size: clamp(17px, 1.8vw, 18px); line-height: 1.3; font-weight: 500; }

p { margin: 0; }
ul, ol { margin: 0; padding: 0; }
img, svg, video { display: block; max-width: 100%; }
img { height: auto; }

a { color: inherit; text-decoration: none; }
button { font: inherit; color: inherit; }

:focus-visible {
  outline: none;
  box-shadow: var(--focus-ring);
  border-radius: var(--radius-xs);
}

/* Long tokens */
.model-code, .break-token { overflow-wrap: anywhere; }

/* ---------- Layout primitives ---------- */
.container {
  width: min(100% - 2 * var(--gutter), var(--container-max));
  margin-inline: auto;
}
.container-wide {
  width: min(100% - 2 * var(--gutter), var(--container-wide));
  margin-inline: auto;
}
.container-narrow {
  width: min(100% - 2 * var(--gutter), var(--container-narrow));
  margin-inline: auto;
}

.section { padding-block: var(--section-y); }
.section-alt { background: var(--color-surface-2); }
.section-dark { background: var(--color-ink-800); color: #fff; }
.section-dark h2, .section-dark h3, .section-dark h4 { color: #fff; }

.eyebrow {
  font-size: var(--text-2xs);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: var(--tracking-eyebrow);
  color: var(--color-steel-500);
  line-height: 1.2;
}
.section-dark .eyebrow { color: var(--color-accent-light); }

.lead {
  font-size: clamp(17px, 2vw, 18px);
  line-height: 1.55;
  max-width: var(--measure-lead);
  color: var(--color-steel-500);
}
.section-dark .lead { color: #C7D2DC; }

.prose { max-width: var(--measure-body); }
.prose p + p { margin-top: var(--space-4); }

.section-head {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-end;
  justify-content: space-between;
  gap: var(--space-4);
  margin-bottom: var(--space-10);
}
.section-head > div { max-width: var(--measure-lead); }
.section-head .eyebrow { margin-bottom: var(--space-3); }
.section-head h2 + .lead { margin-top: var(--space-3); }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  min-height: 44px;
  padding: 0 var(--space-6);
  border: 1px solid transparent;
  border-radius: var(--radius-md);
  font-size: 15px;
  font-weight: 500;
  line-height: 1;
  cursor: pointer;
  text-align: center;
  transition: background-color var(--motion-fast) var(--ease-standard),
              transform var(--motion-fast) var(--ease-standard),
              border-color var(--motion-fast) var(--ease-standard);
}
@media (max-width: 639px) { .btn { font-size: 16px; } }

.btn-primary { background: var(--color-accent); color: var(--color-accent-on); }
.btn-secondary {
  background: var(--color-surface);
  color: var(--color-ink-800);
  border-color: var(--color-line-200);
}
.btn-ghost-dark {
  background: transparent;
  color: #fff;
  border-color: rgba(255, 255, 255, .45);
}
.btn-block { width: 100%; }

@media (hover: hover) {
  .btn-primary:hover { background: var(--color-accent-hover); transform: translateY(-1px); }
  .btn-secondary:hover { border-color: var(--color-ink-600); transform: translateY(-1px); }
  .btn-ghost-dark:hover { border-color: #fff; background: rgba(255, 255, 255, .08); }
}
.btn-primary:active { background: var(--color-accent-active); transform: none; }
.btn:disabled { opacity: .55; cursor: not-allowed; transform: none; }

.link-arrow {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-ink-800);
  border-bottom: 1px solid var(--color-line-200);
  padding-bottom: 2px;
  transition: border-color var(--motion-fast) var(--ease-standard);
}
.section-dark .link-arrow { color: var(--color-accent-light); border-color: rgba(242, 124, 62, .4); }
@media (hover: hover) { .link-arrow:hover { border-color: currentColor; } }

/* ---------- Form fields ---------- */
.field { display: flex; flex-direction: column; gap: var(--space-2); }
.field > label {
  font-size: var(--text-xs);
  font-weight: 500;
  color: var(--color-ink-800);
  line-height: 1.3;
}
.field .req { color: var(--color-accent); }

.field input,
.field select,
.field textarea {
  width: 100%;
  min-height: 48px;
  padding: 10px var(--space-3);
  font-family: inherit;
  font-size: var(--text-sm);
  color: var(--color-ink-800);
  background: var(--color-surface);
  border: 1px solid var(--color-line-200);
  border-radius: var(--radius-sm);
  transition: border-color var(--motion-fast) var(--ease-standard);
}
.field textarea { min-height: 108px; padding-top: var(--space-3); resize: vertical; line-height: 1.5; }
.field input:focus, .field select:focus, .field textarea:focus {
  outline: none;
  border-color: var(--color-ink-600);
  box-shadow: var(--focus-ring);
}
.field input[aria-invalid="true"],
.field select[aria-invalid="true"],
.field textarea[aria-invalid="true"] { border-color: var(--color-danger); }
.field .err { font-size: var(--text-xs); color: var(--color-danger); line-height: 1.4; }
.field .hint { font-size: var(--text-xs); color: var(--color-steel-500); line-height: 1.4; }
.field input::placeholder, .field textarea::placeholder { color: var(--color-steel-300); }

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

.skip-link {
  position: absolute;
  left: var(--space-4);
  top: -60px;
  z-index: 200;
  padding: var(--space-3) var(--space-5);
  background: var(--color-accent);
  color: #fff;
  border-radius: var(--radius-sm);
  font-weight: 500;
  transition: top var(--motion-fast) var(--ease-standard);
}
.skip-link:focus { top: var(--space-4); }

.caption {
  font-size: var(--text-xs);
  line-height: 1.45;
  color: var(--color-steel-500);
  margin-top: var(--space-2);
}
.section-dark .caption { color: #A9B8C6; }

.tabular { font-variant-numeric: tabular-nums; }