/**
 * Sticky header, desktop nav, mega-menu ready, mobile drawer.
 */

.site-header {
  position: sticky;
  top: 0;
  z-index: var(--z-header);
  height: var(--header-height);
  background-color: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid transparent;
  transition:
    border-color var(--duration-fast) var(--ease-standard),
    box-shadow var(--duration-fast) var(--ease-standard);
}

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

[data-theme="dark"] .site-header {
  background-color: rgba(10, 10, 9, 0.92);
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  height: var(--header-height);
}

.site-logo {
  display: inline-flex;
  align-items: center;
  flex-shrink: 0;
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: var(--font-weight-bold);
  letter-spacing: -0.02em;
  color: var(--color-text-primary);
  text-decoration: none;
}

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

.nav-desktop {
  display: none;
  align-items: center;
  gap: var(--space-8);
  margin: 0;
  padding: 0;
  list-style: none;
}

.nav-desktop__link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: var(--space-2) 0;
  font-size: var(--text-small);
  font-weight: var(--font-weight-medium);
  color: var(--color-text-primary);
  text-decoration: none;
  transition: opacity var(--duration-fast) var(--ease-standard);
}

.nav-desktop__link:hover,
.nav-desktop__link:visited {
  color: var(--color-text-primary);
  opacity: 0.7;
  text-decoration: none;
}

.nav-desktop__link[aria-current="page"] {
  opacity: 1;
  box-shadow: inset 0 -2px 0 var(--color-text-primary);
}

.nav-desktop__item--has-mega {
  position: relative;
}

.nav-desktop__trigger {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: var(--space-2) 0;
  border: 0;
  background: transparent;
  font: inherit;
  font-size: var(--text-small);
  font-weight: var(--font-weight-medium);
  color: var(--color-text-primary);
  cursor: pointer;
}

/* Mega menu shell — panel content wired later */
.mega-menu {
  position: absolute;
  top: calc(100% + var(--space-4));
  left: 50%;
  z-index: var(--z-header);
  display: none;
  width: min(100vw - (2 * var(--gutter)), var(--container-xl));
  padding: var(--space-8) 0;
  background: var(--color-bg-elevated);
  border: 1px solid var(--color-border-subtle);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  transform: translate(-50%, -4px);
  opacity: 0;
  pointer-events: none;
  transition:
    opacity var(--duration-normal) var(--ease-standard),
    transform var(--duration-normal) var(--ease-standard);
}

.mega-menu.is-open,
.nav-desktop__item--has-mega:focus-within .mega-menu,
.nav-desktop__item--has-mega[data-mega-open="true"] .mega-menu {
  display: block;
  opacity: 1;
  transform: translate(-50%, 0);
  pointer-events: auto;
}

.mega-menu__grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: var(--space-8);
  width: min(100% - (2 * var(--gutter)), var(--container-xl));
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.nav-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  margin: 0;
  padding: 0;
  border: 0;
  border-radius: var(--radius-md);
  background: transparent;
  color: var(--color-text-primary);
  cursor: pointer;
}

.nav-toggle:hover {
  background: var(--color-hover-surface);
}

.nav-toggle[aria-expanded="true"] .icon-menu {
  display: none;
}

.nav-toggle[aria-expanded="false"] .icon-close,
.nav-toggle:not([aria-expanded="true"]) .icon-close {
  display: none;
}

.nav-toggle[aria-expanded="true"] .icon-close {
  display: block;
}

.mobile-menu {
  position: fixed;
  inset: var(--header-height) 0 0 0;
  z-index: var(--z-mobile-menu);
  display: flex;
  flex-direction: column;
  background: var(--color-bg-canvas);
  transform: translateX(100%);
  visibility: hidden;
  transition:
    transform var(--duration-normal) var(--ease-emphasized),
    visibility var(--duration-normal) var(--ease-emphasized);
}

.mobile-menu.is-open {
  transform: translateX(0);
  visibility: visible;
}

.mobile-menu__panel {
  flex: 1;
  overflow-y: auto;
  padding: var(--space-6) var(--gutter) var(--space-10);
}

.mobile-menu__list {
  margin: 0;
  padding: 0;
  list-style: none;
}

.mobile-menu__link {
  display: block;
  padding: var(--space-4) 0;
  font-size: var(--text-body-lg);
  font-weight: var(--font-weight-medium);
  color: var(--color-text-primary);
  text-decoration: none;
  border-bottom: 1px solid var(--color-border-subtle);
}

.mobile-menu__link:hover,
.mobile-menu__link:visited {
  color: var(--color-text-primary);
  text-decoration: none;
}

.mobile-menu__link[aria-current="page"] {
  color: var(--color-text-primary);
  box-shadow: inset 3px 0 0 var(--color-text-primary);
  padding-left: var(--space-3);
}

body.mobile-menu-open {
  overflow: hidden;
}

@media (min-width: 1024px) {
  .nav-desktop {
    display: flex;
  }

  .nav-toggle,
  .mobile-menu {
    display: none;
  }
}