.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 300;
  height: var(--header-h);
  transition: background var(--duration) var(--ease), border-color var(--duration) var(--ease);
}

@media (max-width: 1023px) {
  .site-header {
    background: rgba(10, 10, 10, 0.85);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--border);
  }
}

.site-header.is-scrolled {
  background: var(--glass);
  backdrop-filter: blur(20px) saturate(1.3);
  -webkit-backdrop-filter: blur(20px) saturate(1.3);
  border-bottom: 1px solid var(--glass-border);
  box-shadow: 0 4px 24px rgba(0, 0, 0, 0.2);
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
  gap: var(--space-lg);
}

.site-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-display);
  font-size: 1.125rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--white);
  flex-shrink: 0;
  transition: opacity var(--duration) var(--ease);
}

.site-logo:hover { opacity: 0.85; }

.site-logo--sm {
  font-size: 1rem;
}

.site-nav {
  display: none;
  align-items: center;
  gap: 4px;
}

.site-nav__group {
  position: relative;
}

.site-nav__trigger {
  display: flex;
  align-items: center;
  gap: 4px;
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--gray-400);
  transition: background var(--duration) var(--ease), color var(--duration) var(--ease);
}

.site-nav__trigger:hover,
.site-nav__group.is-open .site-nav__trigger {
  background: var(--gray-800);
  color: var(--white);
}

.site-nav__trigger svg {
  transition: transform var(--duration) var(--ease);
}

.site-nav__group.is-open .site-nav__trigger svg {
  transform: rotate(180deg);
}

.site-nav__dropdown {
  position: absolute;
  top: calc(100% + 10px);
  left: 0;
  min-width: 280px;
  background: var(--glass);
  backdrop-filter: blur(24px) saturate(1.2);
  -webkit-backdrop-filter: blur(24px) saturate(1.2);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-lg);
  padding: var(--space-sm);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-10px) scale(0.98);
  transition: opacity var(--duration) var(--ease), transform var(--duration) var(--ease-out), visibility var(--duration);
  box-shadow: var(--shadow-lg);
}

.site-nav__group.is-open .site-nav__dropdown {
  opacity: 1;
  visibility: visible;
  transform: translateY(0) scale(1);
}

.site-nav__dropdown-link {
  display: block;
  padding: 12px 14px;
  border-radius: var(--radius-sm);
  transition: background var(--duration) var(--ease);
}

.site-nav__dropdown-link:hover {
  background: var(--gray-800);
}

.site-nav__dropdown-link strong {
  display: block;
  font-size: 0.875rem;
  color: var(--white);
  margin-bottom: 2px;
}

.site-nav__dropdown-link span {
  font-size: 0.75rem;
  color: var(--gray-500);
}

.site-nav__link {
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--gray-400);
  transition: background var(--duration) var(--ease), color var(--duration) var(--ease);
}

.site-nav__link:hover,
.site-nav__link.is-active {
  background: var(--gray-800);
  color: var(--white);
}

.site-header__actions {
  display: flex;
  align-items: center;
  gap: var(--space-md);
}

.site-header__download {
  display: none;
}

/* Mobile toggle */
.menu-toggle {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 5px;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-sm);
  background: transparent;
  border: 1px solid var(--border);
  flex-shrink: 0;
}

.menu-toggle span {
  display: block;
  width: 16px;
  height: 1.5px;
  background: var(--gray-200);
  border-radius: 2px;
  transition: transform 0.25s var(--ease-out), opacity 0.2s var(--ease);
}

.menu-toggle.is-active span:nth-child(1) {
  transform: translateY(6.5px) rotate(45deg);
}

.menu-toggle.is-active span:nth-child(2) {
  opacity: 0;
  transform: scaleX(0);
}

.menu-toggle.is-active span:nth-child(3) {
  transform: translateY(-6.5px) rotate(-45deg);
}

/* Mobile overlay — fully removed from layout when closed */
.mobile-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.65);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  z-index: 400;
}

.mobile-overlay.is-open {
  display: block;
}

/* Mobile sidebar */
.mobile-nav {
  position: fixed;
  top: 0;
  right: 0;
  width: min(320px, 100%);
  height: 100dvh;
  background: var(--gray-950);
  border-left: 1px solid var(--border);
  z-index: 401;
  transform: translateX(100%);
  visibility: hidden;
  pointer-events: none;
  transition: transform 0.35s var(--ease-out), visibility 0s 0.35s;
  display: flex;
  flex-direction: column;
  padding-top: env(safe-area-inset-top);
  padding-bottom: env(safe-area-inset-bottom);
}

.mobile-nav.is-open {
  transform: translateX(0);
  visibility: visible;
  pointer-events: auto;
  transition: transform 0.35s var(--ease-out), visibility 0s 0s;
}

.mobile-nav__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-md);
  height: var(--header-h);
  padding: 0 var(--page-gutter);
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
}

.mobile-nav__close {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-sm);
  color: var(--gray-300);
  border: 1px solid var(--border);
  transition: background var(--duration) var(--ease), color var(--duration) var(--ease);
}

.mobile-nav__close:hover {
  background: var(--gray-800);
  color: var(--white);
}

.mobile-nav__body {
  flex: 1;
  overflow-y: auto;
  overscroll-behavior: contain;
  padding: var(--space-lg) var(--page-gutter);
  -webkit-overflow-scrolling: touch;
}

.mobile-nav__section {
  margin-bottom: var(--space-xl);
}

.mobile-nav__title {
  font-family: var(--font-mono);
  font-size: 0.625rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--gray-500);
  margin-bottom: var(--space-sm);
  padding-left: 2px;
}

.mobile-nav__links {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.mobile-nav__link {
  display: block;
  padding: 12px 14px;
  border-radius: var(--radius-sm);
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--gray-200);
  transition: background var(--duration) var(--ease), color var(--duration) var(--ease);
}

.mobile-nav__link:hover,
.mobile-nav__link:focus-visible {
  background: var(--gray-900);
  color: var(--white);
}

.mobile-nav__link--solo {
  margin-top: var(--space-sm);
  border-top: 1px solid var(--border);
  border-radius: 0;
  padding-top: var(--space-lg);
}

.mobile-nav__foot {
  flex-shrink: 0;
  padding: var(--space-lg) var(--page-gutter);
  border-top: 1px solid var(--border);
  background: rgba(10, 10, 10, 0.95);
}

@media (min-width: 1024px) {
  .site-nav { display: flex; }
  .site-header__download { display: inline-flex; }
  .menu-toggle { display: none; }
  .mobile-nav,
  .mobile-overlay { display: none; }
}

@media (min-width: 640px) and (max-width: 1023px) {
  .site-header__download { display: inline-flex; }
}