/* =========================
   SITE HEADER — plain carbon bar: wordmark, links, one action (Contact)
========================= */

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: var(--carbon);
  color: var(--ink-inverse);
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--header-h);
  padding-inline: var(--margin);
}

.site-header__logo img {
  width: auto;
  height: 1.875rem;
}

/* ---------- Desktop nav ---------- */
.site-nav {
  position: relative;
}

.site-nav__list {
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

.site-nav__link {
  display: inline-flex;
  align-items: center;
  height: 2.75rem;
  padding: 0 0.875rem;
  font-size: var(--step-small);
  font-weight: 400;
  color: var(--ink-inverse-soft);
  transition: opacity 0.3s var(--ease);
}

.site-nav__link:hover,
.site-nav__link[aria-current] {
  color: var(--ink-inverse);
}

/* Contact is the bar's one action: a filled tile one step up from carbon */
.site-nav__list li:last-child {
  margin-left: 0.75rem;
}

.site-nav__list li:last-child .site-nav__link {
  padding: 0 1.25rem;
  background: var(--carbon-3);
  color: var(--ink-inverse);
  font-weight: 600;
  transition: transform 0.35s var(--ease);
}

.site-nav__list li:last-child .site-nav__link:hover {
  transform: translateY(-1px);
}

/* Active-section marker: a 1px-tall bar, scaled to the link width (js/header.js) */
.site-nav__indicator {
  position: absolute;
  left: 0;
  bottom: 0.25rem;
  width: 1px;
  height: 2px;
  background: var(--ink-inverse);
  transform-origin: left;
  opacity: 0;
  pointer-events: none;
}

.site-nav__indicator.is-ready {
  opacity: 1;
}

.site-nav__indicator.is-animated {
  transition: transform 0.5s var(--ease);
}

/* ---------- Mobile toggle ---------- */
.nav-toggle {
  display: none;
  position: relative;
  width: 2.75rem;
  height: 2.75rem;
  margin-right: -0.5rem;
  border: 0;
  background: transparent;
  cursor: pointer;
}

.nav-toggle span {
  position: absolute;
  left: 0.75rem;
  right: 0.75rem;
  height: 2px;
  background: var(--ink-inverse);
  transition: transform 0.35s var(--ease);
}

.nav-toggle span:first-child {
  transform: translateY(-4px);
}

.nav-toggle span:last-child {
  transform: translateY(4px);
}

.nav-toggle[aria-expanded="true"] span:first-child {
  transform: rotate(45deg);
}

.nav-toggle[aria-expanded="true"] span:last-child {
  transform: rotate(-45deg);
}

@media (max-width: 768px) {
  :root {
    --header-h: 3.5rem;
  }

  .nav-toggle {
    display: block;
  }

  .site-nav {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    padding: 0.5rem var(--margin) 1.5rem;
    background: var(--carbon);
    opacity: 0;
    visibility: hidden;
    transform: translate3d(0, -0.5rem, 0);
    transition:
      opacity 0.3s var(--ease),
      transform 0.3s var(--ease),
      visibility 0s linear 0.3s;
  }

  .site-nav.is-open {
    opacity: 1;
    visibility: visible;
    transform: none;
    transition:
      opacity 0.3s var(--ease),
      transform 0.3s var(--ease),
      visibility 0s;
  }

  .site-nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
  }

  .site-nav__link {
    width: 100%;
    height: 3.5rem;
    padding: 0;
    font-size: var(--step-lead);
  }

  .site-nav__list li:last-child {
    margin: 0.75rem 0 0;
  }

  .site-nav__list li:last-child .site-nav__link {
    justify-content: center;
    padding: 0;
  }

  .site-nav__indicator {
    display: none;
  }
}