/* =========================================================================
   Layout — containers, sections, header, footer, grid utilities.
   ========================================================================= */

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

main { flex: 1 0 auto; }

/* ---- Section rhythm ---------------------------------------------------- */
.section {
  padding-block: clamp(var(--space-7), 7vw, var(--space-10));
}
.section--tight { padding-block: var(--space-7); }
.section + .section { padding-top: 0; }

.section-line { border-top: 1px solid var(--line); }

/* Section header with a small index marker (field-manual feel). */
.section-head {
  display: flex;
  align-items: baseline;
  gap: var(--space-4);
  margin-bottom: var(--space-6);
  flex-wrap: wrap;
}
.section-head__title { font-size: var(--step-3); }
.section-head__index {
  font-family: var(--font-mono);
  font-size: var(--step--1);
  color: var(--olive);
  letter-spacing: 0.08em;
}
.section-head__aside { margin-left: auto; }

/* ---- Generic flex/grid helpers --------------------------------------- */
.stack > * + * { margin-top: var(--space-4); }
.stack-lg > * + * { margin-top: var(--space-6); }

.grid { display: grid; gap: var(--space-6); }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-auto {
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
}

.cluster {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
  align-items: center;
}

/* ---- Split layout (content + sticky aside) --------------------------- */
.split {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(var(--space-6), 5vw, var(--space-9));
}
@media (min-width: 940px) {
  .split { grid-template-columns: minmax(0, 1fr) 340px; align-items: start; }
  .split__aside { position: sticky; top: calc(72px + var(--space-5)); }
  .split--aside-left { grid-template-columns: 340px minmax(0, 1fr); }
}

/* ---- Site header ------------------------------------------------------ */
.site-header {
  position: sticky;
  top: 0;
  z-index: var(--z-header);
  background: var(--bg-raised); /* opaque fallback for browsers without color-mix() */
  background: color-mix(in srgb, var(--bg) 86%, transparent);
  backdrop-filter: blur(10px) saturate(120%);
  -webkit-backdrop-filter: blur(10px) saturate(120%);
  border-bottom: 1px solid var(--line);
}
.site-header__inner {
  display: flex;
  align-items: center;
  gap: var(--space-5);
  min-height: 72px;
}
.brand {
  display: inline-flex;
  flex-direction: column;
  line-height: 1.05;
  margin-right: auto;
}
.brand__name {
  font-family: var(--font-display);
  font-size: var(--step-1);
  font-weight: 500;
  letter-spacing: -0.01em;
}
.brand__tag {
  font-family: var(--font-mono);
  font-size: 0.62rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--ink-faint);
  margin-top: 2px;
}

.nav { display: flex; align-items: center; gap: var(--space-5); }
.nav__list {
  display: flex;
  align-items: center;
  gap: clamp(var(--space-3), 2vw, var(--space-5));
}
.nav__link {
  font-size: var(--step--1);
  letter-spacing: 0.01em;
  color: var(--ink-soft);
  padding-block: var(--space-2);
  position: relative;
}
.nav__link:hover,
.nav__link[aria-current="page"] { color: var(--ink); }
.nav__link[aria-current="page"]::after {
  content: "";
  position: absolute;
  left: 0; right: 0; bottom: -2px;
  height: 1px;
  background: var(--olive);
}

.nav__toggle {
  display: none;
  background: none;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  width: 42px; height: 42px;
  cursor: pointer;
  align-items: center;
  justify-content: center;
}
.nav__toggle span,
.nav__toggle span::before,
.nav__toggle span::after {
  content: "";
  display: block;
  width: 18px; height: 1.5px;
  background: var(--ink);
  transition: transform var(--dur) var(--ease), opacity var(--dur) var(--ease);
}
.nav__toggle span::before { transform: translateY(-6px); }
.nav__toggle span::after  { transform: translateY(4.5px); }
.nav__toggle[aria-expanded="true"] span { background: transparent; }
.nav__toggle[aria-expanded="true"] span::before { transform: rotate(45deg); }
.nav__toggle[aria-expanded="true"] span::after  { transform: rotate(-45deg) translateY(-1px); }

/* ---- Mobile nav ------------------------------------------------------- */
@media (max-width: 860px) {
  .nav__toggle { display: inline-flex; }
  .nav {
    position: fixed;
    inset: 72px 0 auto 0;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    background: var(--bg-raised);
    border-bottom: 1px solid var(--line);
    padding: var(--space-4) var(--gutter) var(--space-6);
    transform: translateY(-12px);
    opacity: 0;
    pointer-events: none;
    transition: opacity var(--dur) var(--ease), transform var(--dur) var(--ease);
    max-height: calc(100vh - 72px);
    overflow-y: auto;
  }
  .nav.is-open { opacity: 1; transform: none; pointer-events: auto; }
  .nav__list { flex-direction: column; align-items: stretch; gap: 0; }
  .nav__link {
    padding-block: var(--space-4);
    border-bottom: 1px solid var(--line-faint);
    font-size: var(--step-0);
  }
  .nav .btn { margin-top: var(--space-4); }
}

/* ---- Footer ----------------------------------------------------------- */
.site-footer {
  border-top: 1px solid var(--line);
  background: var(--bg-raised);
  margin-top: var(--space-9);
  padding-block: var(--space-8) var(--space-6);
}
.footer-grid {
  display: grid;
  gap: var(--space-7);
  grid-template-columns: 1.4fr 1fr 1.4fr;
}
.footer-col h4 {
  font-family: var(--font-mono);
  font-size: 0.66rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--ink-faint);
  margin-bottom: var(--space-4);
  font-weight: 500;
}
.footer-col ul { display: grid; gap: var(--space-2); }
.footer-col a { color: var(--ink-soft); font-size: var(--step--1); }
.footer-col a:hover { color: var(--ink); }

.footer-bottom {
  margin-top: var(--space-7);
  padding-top: var(--space-5);
  border-top: 1px solid var(--line);
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-4);
  align-items: center;
  justify-content: space-between;
  color: var(--ink-faint);
  font-size: var(--step--1);
}

@media (max-width: 760px) {
  .grid-2, .grid-3 { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; gap: var(--space-6); }
}
@media (max-width: 920px) and (min-width: 761px) {
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
}