/* ==========================================================================
   Site chrome — the fixed index rail, its mobile drawer, and the footer.
   Shared by every page.
   ========================================================================== */

/* --- Desktop rail ---------------------------------------------------------
   A slim vertical index pinned to the left edge. Content is offset by
   --rail, which collapses to 0 at the drawer breakpoint. */
.system-nav {
  position: fixed;
  inset: 0 auto 0 0;
  z-index: 40;
  display: flex;
  width: var(--rail);
  flex-direction: column;
  padding: 1.25rem 0 1rem;
  background: var(--ink);
  color: var(--paper);
  --focus-ring: var(--acid);
}

.system-nav__identity {
  display: grid;
  padding: 1rem 0 1.15rem;
  place-items: center;
  color: var(--paper);
  font-size: 1.2rem;
  font-weight: 700;
  letter-spacing: -0.13em;
  text-decoration: none;
}

.system-nav__thin {
  color: var(--acid);
}

.system-nav__rule {
  height: 1px;
  background: var(--rule-light);
}

.system-nav nav {
  display: flex;
  flex: 1;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 1.7rem;
}

.system-nav__link {
  position: relative;
  /* The rail runs vertically, so the block axis is the visual horizontal one.
     This padding is what gives a rotated label a large enough hit area. */
  padding-block: 0.55rem;
  color: rgba(247, 241, 230, 0.62);
  font-size: var(--text-xs);
  font-weight: 700;
  letter-spacing: 0.04em;
  text-decoration: none;
  text-transform: uppercase;
  writing-mode: vertical-rl;
  transform: rotate(180deg);
  transition: color var(--dur);
}

.system-nav__link span {
  color: var(--acid);
  font-size: 0.55rem;
  font-weight: 400;
  letter-spacing: 0.08em;
}

.system-nav__link::before {
  position: absolute;
  top: -0.65rem;
  right: 50%;
  width: 0.22rem;
  height: 0.22rem;
  border-radius: 50%;
  background: var(--acid);
  content: '';
  opacity: 0;
  transition: opacity var(--dur);
}

.system-nav__link:hover,
.system-nav__link.is-current {
  color: var(--paper);
}

.system-nav__link.is-current::before {
  opacity: 1;
}

.system-nav__external {
  display: none;
}

/* --- Mobile drawer toggle -------------------------------------------------- */
.system-toggle {
  display: none;
}

.system-scrim {
  display: none;
}

main {
  margin-left: var(--rail);
}

/* --- Footer ---------------------------------------------------------------- */
.site-footer {
  margin-left: var(--rail);
  padding: var(--space-2xl) var(--gutter) var(--space-xl);
  background: var(--ink);
  color: var(--on-ink);
  --focus-ring: var(--acid);
}

.site-footer__grid {
  display: grid;
  grid-template-columns: minmax(0, 1.3fr) repeat(2, minmax(0, 0.7fr));
  gap: var(--space-xl) var(--space-lg);
}

.site-footer__wordmark {
  margin: 0 0 var(--space-sm);
  color: var(--paper);
  font-size: var(--display-xs);
  font-weight: 700;
  letter-spacing: -0.06em;
  line-height: 1;
}

.site-footer__blurb {
  max-width: 22rem;
  color: var(--on-ink);
  font-size: var(--text-md);
}

.site-footer h2 {
  margin: 0 0 var(--space-sm);
  color: var(--acid);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 400;
  letter-spacing: var(--tracking-label);
  text-transform: uppercase;
}

.site-footer ul {
  display: grid;
  gap: 0.15rem;
}

/* 2.5rem keeps these comfortably thumb-sized. At the previous padding they
   measured 32px tall — over the 24px WCAG minimum, but tight in a stacked
   list where the next link is a few pixels away. */
.site-footer a {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  min-height: 2.5rem;
  padding: 0.3rem 0;
  color: var(--on-ink);
  font-size: var(--text-md);
  text-decoration: none;
  transition: color var(--dur-fast);
}

.site-footer a:hover {
  color: var(--acid);
}

.site-footer__baseline {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: var(--space-sm);
  margin-top: var(--space-2xl);
  border-top: 1px solid var(--rule-light);
  padding-top: var(--space-sm);
  color: rgba(247, 241, 230, 0.66);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.site-footer__baseline a {
  color: rgba(247, 241, 230, 0.66);
  font-family: inherit;
  font-size: inherit;
  letter-spacing: inherit;
  text-transform: inherit;
}

/* ==========================================================================
   Drawer breakpoint — tablet and below get a real drawer instead of a rail.
   ========================================================================== */
@media (max-width: 60rem) {
  .system-toggle {
    position: fixed;
    top: 0.75rem;
    right: 0.75rem;
    z-index: 55;
    display: inline-flex;
    align-items: center;
    gap: 0.45rem;
    min-height: 2.75rem;
    border: 1px solid var(--ink);
    padding: 0.55rem 0.8rem;
    background: var(--paper);
    color: var(--ink);
    font-size: var(--text-xs);
    font-weight: 700;
    letter-spacing: 0.07em;
    text-transform: uppercase;
  }

  .system-toggle__mark {
    width: 0.48rem;
    height: 0.48rem;
    border-radius: 50%;
    background: var(--coral);
  }

  .system-toggle[aria-expanded='true'] {
    border-color: var(--paper);
    background: var(--ink);
    color: var(--paper);
    --focus-ring: var(--acid);
  }

  .system-toggle[aria-expanded='true'] .system-toggle__mark {
    background: var(--acid);
  }

  .system-scrim {
    position: fixed;
    inset: 0;
    z-index: 44;
    display: block;
    border: 0;
    padding: 0;
    background: rgba(13, 15, 28, 0.55);
    opacity: 0;
    pointer-events: none;
    transition: opacity var(--dur) var(--ease-out);
  }

  .system-scrim.is-active {
    opacity: 1;
    pointer-events: auto;
  }

  .system-nav {
    z-index: 50;
    width: min(20rem, 86vw);
    padding: 1.2rem;
    /* `visibility` keeps the closed drawer out of the tab order even before
       the `inert` attribute is applied by script. */
    visibility: hidden;
    transform: translateX(-102%);
    box-shadow: 8px 0 34px rgba(21, 23, 42, 0.28);
    transition:
      transform var(--dur) var(--ease-out),
      visibility 0s linear var(--dur);
  }

  .system-nav.is-open {
    visibility: visible;
    transform: translateX(0);
    transition-delay: 0s;
  }

  .system-nav__identity {
    grid-template-columns: auto auto;
    justify-content: start;
    padding-bottom: 1.2rem;
  }

  .system-nav__rule {
    margin: 0 -1.2rem;
  }

  .system-nav nav {
    align-items: stretch;
    justify-content: start;
    gap: 0.1rem;
    padding: 1.75rem 0;
    overflow-y: auto;
  }

  .system-nav__link {
    display: flex;
    align-items: baseline;
    gap: 0.8rem;
    min-height: 2.75rem;
    padding: 0.55rem 0;
    color: var(--paper);
    font-size: 1rem;
    writing-mode: horizontal-tb;
    transform: none;
  }

  .system-nav__link::before {
    display: none;
  }

  .system-nav__link.is-current {
    color: var(--acid);
  }

  .system-nav__external {
    display: flex;
    flex-direction: column;
    gap: 0.2rem;
    border-top: 1px solid var(--rule-light);
    padding-top: var(--space-sm);
  }

  .system-nav__external a {
    display: flex;
    align-items: center;
    justify-content: space-between;
    min-height: 2.75rem;
    color: rgba(247, 241, 230, 0.78);
    font-size: var(--text-md);
    text-decoration: none;
  }

  .system-nav__external span {
    color: var(--acid);
  }

  main,
  .site-footer {
    margin-left: 0;
  }

  .site-footer__grid {
    grid-template-columns: 1fr;
    gap: var(--space-lg);
  }
}

/* Locks the page behind an open drawer without the scroll position jumping. */
body.is-nav-open {
  overflow: hidden;
}