/* ==========================================================================
   Header / Primary Navigation
   Alcodex Technologies

   Consumes tokens from variables.css only — no new hardcoded values.
   Desktop: inline nav with click/keyboard-toggled dropdowns.
   Mobile (<64rem): nav collapses into a toggled panel; dropdowns become
   accordions within it. Behaviour lives in js/main.js.
   ========================================================================== */

/* --------------------------------------------------------------------
   Mobile menu open: lock background scroll (class set in js/main.js)
   -------------------------------------------------------------------- */

@media (max-width: 63.9375rem) {
  body.nav-open {
    overflow: hidden;
  }
}

/* --------------------------------------------------------------------
   Skip link
   -------------------------------------------------------------------- */

.skip-link {
  position: absolute;
  top: -3rem;
  left: var(--space-4);
  z-index: var(--z-max);
  padding: var(--space-2) var(--space-4);
  background-color: var(--color-brand);
  color: var(--color-text-inverse);
  border-radius: var(--radius-md);
  text-decoration: none;
  transition: top var(--transition-fast);
}

.skip-link:focus {
  top: var(--space-4);
}

/* --------------------------------------------------------------------
   Header shell
   -------------------------------------------------------------------- */

.site-header {
  position: sticky;
  top: 0;
  z-index: var(--z-sticky);
  background-color: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  transition: box-shadow var(--transition-base), border-color var(--transition-base), background-color var(--transition-base);
}

.site-header.is-scrolled {
  box-shadow: var(--shadow-sm);
  border-color: var(--color-border);
}

.site-header-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4) var(--space-8);
  padding-block: var(--space-3);
}

/* --------------------------------------------------------------------
   Brand
   -------------------------------------------------------------------- */

.site-logo {
  display: inline-flex;
  align-items: center;
  flex-shrink: 0;
  max-width: 100%;
  line-height: 1;
  text-decoration: none;
}

.site-logo img {
  display: block;
  width: 13.75rem;
  max-width: 100%;
  height: auto;
}

.site-logo:hover,
.site-logo:focus-visible {
  color: var(--color-text-primary);
  text-decoration: none;
}

/* --------------------------------------------------------------------
   Desktop navigation
   -------------------------------------------------------------------- */

.site-nav {
  order: 2;
}

.nav-list {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  padding: var(--space-1);
  border: 0;
  background: transparent;
  list-style: none;
}

.nav-item {
  position: relative;
}

.nav-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
  font-weight: var(--font-weight-medium);
  color: var(--color-text-secondary);
  white-space: nowrap;
}

.nav-link:hover,
.nav-link:focus-visible,
.nav-item.is-open > .nav-link {
  background: var(--color-brand-subtle);
  color: var(--color-brand-hover);
  text-decoration: none;
}

.nav-caret {
  color: var(--color-text-muted);
  transition: transform var(--transition-base);
}

.nav-item.is-open .nav-caret,
.nav-item.has-dropdown:focus-within .nav-caret {
  transform: rotate(180deg);
}

.nav-dropdown {
  position: absolute;
  top: calc(100% + var(--space-2));
  left: 0;
  min-width: 13.75rem;
  margin-top: 0;
  padding: var(--space-2);
  list-style: none;
  background-color: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  opacity: 0;
  visibility: hidden;
  transform: translateY(6px);
  transition: opacity var(--transition-base),
              transform var(--transition-base),
              visibility var(--transition-base);
  z-index: var(--z-dropdown);
}

/* Wider variant for the Products dropdown, whose labels ("Water
   Quality Monitoring") are longer than the other menus' — only this
   dropdown gets the extra width. */
.nav-dropdown--wide {
  min-width: 16rem;
}

.nav-item.is-open > .nav-dropdown,
.nav-item.has-dropdown:focus-within > .nav-dropdown {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.nav-dropdown-link {
  display: block;
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  text-decoration: none;
}

.nav-dropdown-link:hover,
.nav-dropdown-link:focus-visible {
  background: var(--color-brand-subtle);
  color: var(--color-text-primary);
  text-decoration: none;
}

/* --------------------------------------------------------------------
   Header actions (CTA + mobile toggle)
   -------------------------------------------------------------------- */

.site-header-actions {
  order: 3;
  display: flex;
  align-items: center;
  gap: var(--space-4);
}

.site-cta {
  min-height: 2.75rem;
}

.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 0.3125rem;
  width: 2.75rem;
  height: 2.75rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  flex-shrink: 0;
}

.nav-toggle-bar {
  width: 1.25rem;
  height: 2px;
  background-color: var(--color-text-primary);
  border-radius: var(--radius-full);
  transition: transform var(--transition-fast), opacity var(--transition-fast);
}

.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(1) {
  transform: translateY(0.4375rem) rotate(45deg);
}

.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(2) {
  opacity: 0;
}

.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(3) {
  transform: translateY(-0.4375rem) rotate(-45deg);
}

/* --------------------------------------------------------------------
   Mobile navigation (<64rem)
   -------------------------------------------------------------------- */

@media (max-width: 63.9375rem) {
  .nav-toggle {
    display: flex;
  }

  .site-nav {
    display: none;
    order: 4;
    flex-basis: 100%;
    max-height: calc(100dvh - 6rem);
    overflow-y: auto;
    margin-top: var(--space-4);
    padding-top: var(--space-4);
    border-top: 1px solid var(--color-border);
  }

  .site-nav.is-open {
    display: block;
  }

  .nav-list {
    flex-direction: column;
    align-items: stretch;
    gap: var(--space-1);
    padding: 0;
    border: 0;
    border-radius: 0;
    background: transparent;
  }

  .nav-link {
    width: 100%;
    justify-content: space-between;
    padding: var(--space-3) var(--space-2);
    font-size: var(--text-base);
  }

  .nav-dropdown {
    position: static;
    min-width: 0;
    margin-top: 0;
    padding: 0 0 0 var(--space-4);
    border: none;
    box-shadow: none;
    opacity: 1;
    visibility: visible;
    transform: none;
    max-height: 0;
    overflow: hidden;
    transition: max-height var(--transition-base);
  }

  .nav-item.is-open > .nav-dropdown {
    max-height: 32rem;
    padding-top: var(--space-1);
    padding-bottom: var(--space-2);
  }
}

@media (prefers-reduced-motion: reduce) {
  .nav-dropdown,
  .nav-toggle-bar,
  .nav-caret {
    transition: none;
  }
}

@media (max-width: 36rem) {
  .site-header-inner {
    gap: var(--space-3);
  }

  .site-header .site-logo img {
    width: 13rem;
  }

  /* Contact remains in the About menu and page enquiry actions. */
  .site-cta {
    display: none;
  }
}