/* ============================================================================
   SITE HEADER — Evident Technologies (CANONICAL VERSION 1.0.0)
   ============================================================================
   
   DO NOT MODIFY WITHOUT ARCHITECTURAL REVIEW
   
   This is the finalized, court-defensible header component for Evident.
   
   Features:
   - Sticky positioning with proper z-index layering
   - Dual logo variants (light/dark) with theme-aware switching
   - Accessible desktop navigation with ARIA landmarks
   - Keyboard-navigable dropdown menus
   - Mobile-first responsive drawer with focus trap & scroll-lock
   - Full WCAG 2.1 AA compliance
   - BEM methodology throughout
   
   Dependencies:
   - HTML: /src/_includes/header.njk
   - JavaScript: /src/assets/js/menu.js
   - Tokens: /assets/css/tokens/evident-design-tokens.css
   
   Last locked: 2026-02-11
   ============================================================================ */

/* ---- Shell ---- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.72);
  backdrop-filter: blur(16px) saturate(1.6);
  -webkit-backdrop-filter: blur(16px) saturate(1.6);
  border-bottom: 1px solid rgba(229, 231, 235, 0.5);
  font-family: 'Inter', system-ui, -apple-system, 'Segoe UI', sans-serif;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.04);
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1rem;
  height: 4rem;
}

/* ---- Brand / Logo ---- */
.site-header__brand {
  display: flex;
  align-items: center;
  flex-shrink: 0;
  text-decoration: none;
}

.site-header__logo {
  height: 2rem;
  width: auto;
  display: block;
}

/* Light logo for white header (default) — hide dark */
.site-header__logo--dark {
  display: none;
}

/* Dark-mode: show dark-variant (white text), hide light-variant */
[data-theme='dark'] .site-header__logo--light {
  display: none;
}
[data-theme='dark'] .site-header__logo--dark {
  display: block;
}

/* ---- Desktop navigation ---- */
.site-header__nav {
  display: none;
}

.site-header__menu {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.site-header__item {
  position: relative;
}

.site-header__link {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  padding: 0.5rem 0.75rem;
  font-size: 0.9375rem;
  font-weight: 500;
  color: #374151;
  text-decoration: none;
  border: none;
  background: none;
  border-radius: 6px;
  cursor: pointer;
  transition: color 0.15s ease, background-color 0.15s ease;
  white-space: nowrap;
  line-height: 1.5;
}

.site-header__link:hover,
.site-header__link:focus-visible {
  color: #0b73d2;
  background-color: #f3f4f6;
}

.site-header__link:focus-visible {
  outline: 2px solid #0b73d2;
  outline-offset: 2px;
}

.site-header__chevron {
  transition: transform 0.2s ease;
  flex-shrink: 0;
}

.site-header__link[aria-expanded='true'] .site-header__chevron {
  transform: rotate(180deg);
}

/* ---- Dropdown ---- */
.site-header__dropdown {
  position: absolute;
  top: calc(100% + 0.5rem);
  left: 50%;
  transform: translateX(-50%);
  min-width: 14rem;
  background: rgba(255, 255, 255, 0.82);
  backdrop-filter: blur(20px) saturate(1.5);
  -webkit-backdrop-filter: blur(20px) saturate(1.5);
  border: 1px solid rgba(255, 255, 255, 0.6);
  border-radius: 12px;
  box-shadow:
    0 8px 32px rgba(0, 0, 0, 0.08),
    0 2px 8px rgba(0, 0, 0, 0.04),
    inset 0 1px 0 rgba(255, 255, 255, 0.7);
  padding: 0.5rem;
  list-style: none;
  margin: 0;
  opacity: 0;
  visibility: hidden;
  transform: translateX(-50%) translateY(-8px);
  transition:
    opacity 0.2s ease,
    visibility 0.2s ease,
    transform 0.2s ease;
  z-index: 110;
}

.site-header__dropdown.is-open {
  opacity: 1;
  visibility: visible;
  transform: translateX(-50%) translateY(0);
}

.site-header__dropdown-link {
  display: block;
  padding: 0.625rem 0.75rem;
  font-size: 0.9375rem;
  font-weight: 450;
  color: #374151;
  text-decoration: none;
  border-radius: 8px;
  transition: color 0.15s ease, background-color 0.15s ease;
}

.site-header__dropdown-link:hover,
.site-header__dropdown-link:focus-visible {
  color: #0b73d2;
  background-color: #f3f4f6;
}

.site-header__dropdown-link:focus-visible {
  outline: 2px solid #0b73d2;
  outline-offset: -2px;
}

/* ---- CTA buttons ---- */
.site-header__actions {
  display: none;
  align-items: center;
  gap: 0.75rem;
  flex-shrink: 0;
}

.site-header__btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.5rem 1.125rem;
  font-size: 0.875rem;
  font-weight: 600;
  line-height: 1.5;
  border-radius: 6px;
  text-decoration: none;
  cursor: pointer;
  border: none;
  transition:
    color 0.15s ease,
    background-color 0.15s ease,
    box-shadow 0.15s ease;
  white-space: nowrap;
}

.site-header__btn:focus-visible {
  outline: 2px solid #0b73d2;
  outline-offset: 2px;
}

.site-header__btn--ghost {
  color: #374151;
  background: transparent;
}

.site-header__btn--ghost:hover {
  color: #0b73d2;
  background-color: #f3f4f6;
}

.site-header__btn--primary {
  color: #fff;
  background: linear-gradient(135deg, #0b73d2 0%, #0962b3 100%);
  box-shadow:
    0 1px 3px rgba(0, 0, 0, 0.1),
    0 4px 12px rgba(11, 115, 210, 0.25);
}

.site-header__btn--primary:hover {
  background: linear-gradient(135deg, #0962b3 0%, #084a92 100%);
  box-shadow:
    0 2px 6px rgba(0, 0, 0, 0.12),
    0 8px 20px rgba(11, 115, 210, 0.3);
  transform: translateY(-1px);
}

/* ---- Mobile toggle ---- */
.site-header__mobile-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.5rem;
  padding: 0;
  border: none;
  background: none;
  color: #374151;
  border-radius: 6px;
  cursor: pointer;
  transition: color 0.15s ease, background-color 0.15s ease;
}

.site-header__mobile-toggle:hover {
  background-color: #f3f4f6;
}

.site-header__mobile-toggle:focus-visible {
  outline: 2px solid #0b73d2;
  outline-offset: 2px;
}

/* Hamburger / close icon swap */
.site-header__close {
  display: none;
}

.site-header__mobile-toggle[aria-expanded='true'] .site-header__hamburger {
  display: none;
}

.site-header__mobile-toggle[aria-expanded='true'] .site-header__close {
  display: block;
}

/* ---- Mobile drawer ---- */
.site-header__drawer {
  position: fixed;
  inset: 4rem 0 0 0;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(20px) saturate(1.4);
  -webkit-backdrop-filter: blur(20px) saturate(1.4);
  z-index: 99;
  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
  padding: 1.5rem 1.25rem 2rem;
  transform: translateX(100%);
  transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  visibility: hidden;
}

.site-header__drawer.is-open {
  transform: translateX(0);
  visibility: visible;
}

.site-header__drawer-menu {
  list-style: none;
  margin: 0;
  padding: 0;
}

.site-header__drawer-link {
  display: block;
  padding: 0.875rem 0;
  font-size: 1.0625rem;
  font-weight: 500;
  color: #1a1a2e;
  text-decoration: none;
  border-bottom: 1px solid #f3f4f6;
  cursor: pointer;
}

.site-header__drawer-link:hover,
.site-header__drawer-link:focus-visible {
  color: #0b73d2;
}

.site-header__drawer-link:focus-visible {
  outline: 2px solid #0b73d2;
  outline-offset: 2px;
}

.site-header__drawer-details {
  border-bottom: 1px solid #f3f4f6;
}

.site-header__drawer-details summary {
  list-style: none;
}

.site-header__drawer-details summary::-webkit-details-marker {
  display: none;
}

.site-header__drawer-details summary::after {
  content: '';
  display: inline-block;
  width: 0.5rem;
  height: 0.5rem;
  margin-left: 0.5rem;
  border-right: 2px solid currentColor;
  border-bottom: 2px solid currentColor;
  transform: rotate(45deg);
  transition: transform 0.2s ease;
  vertical-align: middle;
}

.site-header__drawer-details[open] summary::after {
  transform: rotate(-135deg);
}

.site-header__drawer-sub {
  list-style: none;
  margin: 0;
  padding: 0 0 0.5rem 1rem;
}

.site-header__drawer-sublink {
  display: block;
  padding: 0.625rem 0;
  font-size: 0.9375rem;
  font-weight: 450;
  color: #6b7280;
  text-decoration: none;
  transition: color 0.15s ease;
}

.site-header__drawer-sublink:hover,
.site-header__drawer-sublink:focus-visible {
  color: #0b73d2;
}

.site-header__drawer-actions {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  margin-top: 1.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid #e5e7eb;
}

.site-header__drawer-actions .site-header__btn {
  width: 100%;
  justify-content: center;
  padding: 0.75rem 1rem;
  font-size: 1rem;
}

/* ---- Desktop breakpoint (768px+) ---- */
@media (min-width: 768px) {
  .site-header__nav {
    display: flex;
  }

  .site-header__actions {
    display: flex;
  }

  .site-header__mobile-toggle {
    display: none;
  }

  .site-header__drawer {
    display: none;
  }
}

/* ---- Dark mode ---- */
[data-theme='dark'] .site-header {
  background: rgba(17, 24, 39, 0.82);
  backdrop-filter: blur(16px) saturate(1.6);
  -webkit-backdrop-filter: blur(16px) saturate(1.6);
  border-bottom-color: rgba(31, 41, 55, 0.5);
}

[data-theme='dark'] .site-header__link {
  color: #d1d5db;
}

[data-theme='dark'] .site-header__link:hover,
[data-theme='dark'] .site-header__link:focus-visible {
  color: #60a5fa;
  background-color: #1f2937;
}

[data-theme='dark'] .site-header__dropdown {
  background-color: #1f2937;
  border-color: #374151;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.3);
}

[data-theme='dark'] .site-header__dropdown-link {
  color: #d1d5db;
}

[data-theme='dark'] .site-header__dropdown-link:hover,
[data-theme='dark'] .site-header__dropdown-link:focus-visible {
  color: #60a5fa;
  background-color: #374151;
}

[data-theme='dark'] .site-header__btn--ghost {
  color: #d1d5db;
}

[data-theme='dark'] .site-header__btn--ghost:hover {
  color: #60a5fa;
  background-color: #1f2937;
}

[data-theme='dark'] .site-header__mobile-toggle {
  color: #d1d5db;
}

[data-theme='dark'] .site-header__mobile-toggle:hover {
  background-color: #1f2937;
}

[data-theme='dark'] .site-header__drawer {
  background-color: #111827;
}

[data-theme='dark'] .site-header__drawer-link {
  color: #e5e7eb;
  border-bottom-color: #1f2937;
}

[data-theme='dark'] .site-header__drawer-link:hover {
  color: #60a5fa;
}

[data-theme='dark'] .site-header__drawer-details {
  border-bottom-color: #1f2937;
}

[data-theme='dark'] .site-header__drawer-sublink {
  color: #9ca3af;
}

[data-theme='dark'] .site-header__drawer-sublink:hover {
  color: #60a5fa;
}

[data-theme='dark'] .site-header__drawer-actions {
  border-top-color: #1f2937;
}

/* ---- Reduced motion ---- */
@media (prefers-reduced-motion: reduce) {
  .site-header__dropdown,
  .site-header__drawer,
  .site-header__chevron,
  .site-header__link,
  .site-header__btn {
    transition: none;
  }
}