/* ==========================================================================
   Layout — containers, section rhythm, the light/muted/dark section system,
   and the structural (non-visual-detail) shape of header/footer.
   ========================================================================== */

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

/* ---- Section rhythm & the light / muted / dark system ----
   Every homepage section (Milestone M2) is one .section with a light,
   muted, or dark modifier. Color tokens are re-scoped per section in
   tokens.css, so buttons/cards/links inside automatically adapt — a
   .btn--primary on a dark section still reads correctly with no extra class. */
.section {
  background: var(--color-bg);
  color: var(--color-text);
  padding-block: var(--space-8);
  transition: background var(--duration-slow) var(--ease-standard);
}

@media (min-width: 768px) {
  .section {
    padding-block: var(--space-9);
  }
}

@media (min-width: 1024px) {
  .section {
    padding-block: var(--space-10);
  }
}

.section--dark a:not(.btn) {
  text-decoration-color: var(--color-accent);
}

/* ---- Site header ---- */
.site-header {
  position: sticky;
  top: 0;
  z-index: var(--z-header);
  background: var(--white);
  border-bottom: 1px solid transparent;
  transition: box-shadow var(--duration-base) var(--ease-standard),
    border-color var(--duration-base) var(--ease-standard),
    background var(--duration-base) var(--ease-standard);
}

/* Glass only once scrolled past the hero — a solid header reads cleaner
   at rest, and the frosted effect then has page content behind it to
   actually blur, rather than blurring plain white-on-white. */
.site-header.is-scrolled {
  background: rgba(255, 255, 255, 0.72);
  backdrop-filter: blur(14px) saturate(160%);
  -webkit-backdrop-filter: blur(14px) saturate(160%);
  border-color: var(--color-border);
  box-shadow: var(--shadow-sm);
}

.site-header__inner {
  max-width: var(--content-max-width);
  margin-inline: auto;
  padding-inline: var(--content-padding-inline);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-5);
  min-height: 72px;
}

/* ---- Site footer ---- */
.site-footer {
  background: var(--green-deep);
  color: var(--white);
}

.site-footer__inner {
  max-width: var(--content-max-width);
  margin-inline: auto;
  padding: var(--space-8) var(--content-padding-inline);
  display: grid;
  gap: var(--space-6);
}

@media (min-width: 768px) {
  .site-footer__inner {
    grid-template-columns: 1.2fr 1fr;
    align-items: start;
  }
}

@media (min-width: 1024px) {
  .site-footer__inner {
    grid-template-columns: 1.4fr 1fr 1fr;
  }

  .site-footer__links,
  .site-footer__legal,
  .site-footer__credit {
    grid-column: 1 / -1;
  }
}

.site-footer__actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
}

.site-footer__links {
  display: flex;
  gap: var(--space-4);
}

/* ---- Utility layout primitives used by components ---- */
.stack {
  display: flex;
  flex-direction: column;
}

.cluster {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
}

.grid {
  display: grid;
  gap: var(--space-6);
}

@media (min-width: 768px) {
  .grid--2 {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 768px) {
  .grid--3 {
    grid-template-columns: repeat(2, 1fr);
  }
}

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