/* layout.css — section containers, grid + flex primitives, viewport guards. */

/* The site uses CSS Grid for page-level layout and Flexbox for component-level. */

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

.container--wide { max-width: var(--content-wide); }

.section {
  padding-block: clamp(var(--s-8), 10vw, var(--s-10));
  position: relative;
}

.section--tight { padding-block: clamp(var(--s-6), 7vw, var(--s-8)); }

.section--dark    { background: var(--ink); }
.section--surface { background: var(--ink-2); }
.section--elevated { background: var(--ink-3); }

.divider { height: 1px; background: var(--rule); }

/* Grid presets */
.grid { display: grid; gap: var(--s-5); }
.grid--2 { grid-template-columns: 1fr; }
.grid--3 { grid-template-columns: 1fr; }
.grid--4 { grid-template-columns: 1fr; }

@media (min-width: 640px) {
  .grid--2 { grid-template-columns: repeat(2, 1fr); }
  .grid--3 { grid-template-columns: repeat(2, 1fr); }
  .grid--4 { grid-template-columns: repeat(2, 1fr); }
}
@media (min-width: 1024px) {
  .grid--3 { grid-template-columns: repeat(3, 1fr); }
  .grid--4 { grid-template-columns: repeat(4, 1fr); }
}

/* Two-column capability detail (copy + visual). */
.split {
  display: grid;
  gap: var(--s-6);
  grid-template-columns: 1fr;
}
@media (min-width: 1024px) {
  .split { grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: var(--s-8); align-items: center; }
  .split--copy-right > :first-child { order: 2; }
}

.stack > * + * { margin-top: var(--s-4); }
.stack--lg > * + * { margin-top: var(--s-6); }
.stack--xl > * + * { margin-top: var(--s-8); }

.row {
  display: flex;
  gap: var(--s-3);
  flex-wrap: wrap;
  align-items: center;
}
.row--end { justify-content: flex-end; }
.row--between { justify-content: space-between; }

/* Spoke layout — sticky left rail TOC on desktop, top progress on tablet, bottom sheet on mobile. */
.spoke-layout {
  display: grid;
  gap: var(--s-6);
  grid-template-columns: 1fr;
}
@media (min-width: 1024px) {
  .spoke-layout {
    grid-template-columns: 280px minmax(0, 1fr);
    gap: var(--s-8);
  }
}

.spoke-toc {
  display: none;
}
@media (min-width: 1024px) {
  .spoke-toc {
    display: block;
    position: sticky;
    top: 96px;
    align-self: start;
    max-height: calc(100vh - 120px);
    overflow-y: auto;
    padding-block: var(--s-2);
  }
  .spoke-toc ol { list-style: none; padding: 0; margin: 0; }
  .spoke-toc li { font-size: var(--fs-caption); padding-block: var(--s-2); border-left: 2px solid transparent; padding-inline-start: var(--s-3); transition: border-color var(--dur-fast), color var(--dur-fast); color: var(--bone-faint); }
  .spoke-toc li[data-active="true"] { border-left-color: var(--accent); color: var(--bone); }
  .spoke-toc a { display: block; }
}

/* Hide-only helpers — never display:none for accessibility. */
.visually-hidden {
  position: absolute !important;
  width: 1px; height: 1px;
  padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0,0,0,0);
  white-space: nowrap; border: 0;
}

/* Section reveal — works with reveal.js IntersectionObserver. */
[data-reveal] {
  opacity: 0;
  transform: translateY(12px);
  transition: opacity var(--dur-slow) var(--ease-out-expo), transform var(--dur-slow) var(--ease-out-expo);
}
[data-reveal][data-revealed="true"] {
  opacity: 1;
  transform: none;
}
@media (prefers-reduced-motion: reduce) {
  [data-reveal] { opacity: 1; transform: none; }
}