.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  width: 100%;
  border-bottom: 1px solid transparent;
  background: rgba(252, 254, 255, 0.78);
  backdrop-filter: blur(18px) saturate(120%);
  -webkit-backdrop-filter: blur(18px) saturate(120%);
  transition: background-color var(--transition-base), border-color var(--transition-base), box-shadow var(--transition-base);
}

.site-header.is-scrolled {
  border-bottom-color: var(--color-line);
  background: rgba(252, 254, 255, 0.94);
  box-shadow: 0 5px 18px rgba(34, 79, 111, 0.06);
}

.site-header__inner {
  display: flex;
  min-height: 4.75rem;
  align-items: center;
  gap: var(--space-4);
}

.site-header__brand,
.site-footer__brand {
  display: inline-flex;
  min-width: 0;
  flex: 0 1 auto;
  align-items: center;
  gap: 0.625rem;
  color: var(--color-ink);
  font-family: var(--font-heading);
  font-size: 1.125rem;
  font-weight: var(--weight-extrabold);
  letter-spacing: -0.04em;
  line-height: 1.15;
  text-decoration: none;
}

.site-header__brand:hover {
  color: var(--color-primary-hover);
}

.site-header__logo {
  width: 2.375rem;
  height: 2.375rem;
  flex: 0 0 2.375rem;
  object-fit: contain;
}

.site-header__brand-text {
  min-width: 0;
  white-space: nowrap;
}

.site-header__brand-short {
  display: none;
}

.site-header__nav {
  min-width: 0;
  margin-left: auto;
}

.site-header__nav-list {
  display: flex;
  align-items: center;
  gap: clamp(0.625rem, 1.35vw, 1.25rem);
  margin: 0;
  padding: 0;
  list-style: none;
}

.site-header__nav-list li,
.site-header__nav-list li + li {
  margin: 0;
  padding: 0;
}

.site-header__nav-list a,
.site-header__contact {
  display: inline-flex;
  min-height: 2.75rem;
  align-items: center;
  color: var(--color-ink);
  font-size: 0.8125rem;
  font-weight: var(--weight-semibold);
  line-height: 1.2;
  text-decoration: none;
  white-space: nowrap;
}

.site-header__nav-list a::after,
.site-header__contact::after {
  position: absolute;
  right: 0;
  bottom: 0.3rem;
  left: 0;
  height: 2px;
  transform: scaleX(0);
  transform-origin: left;
  background: var(--color-celestine);
  content: "";
  transition: transform var(--transition-fast);
}

.site-header__nav-list a,
.site-header__contact {
  position: relative;
}

.site-header__nav-list a:hover,
.site-header__nav-list a[aria-current="page"],
.site-header__contact:hover {
  color: var(--color-primary);
}

.site-header__nav-list a:hover::after,
.site-header__nav-list a[aria-current="page"]::after,
.site-header__contact:hover::after {
  transform: scaleX(1);
}

.site-header__actions {
  display: flex;
  flex: 0 0 auto;
  align-items: center;
  gap: var(--space-3);
}

.site-header__download {
  min-height: 2.5rem;
  padding-inline: 0.8rem;
  font-size: 0.75rem;
  white-space: nowrap;
}

.site-header__toggle,
.site-header__mobile-action,
.site-header__nav-mobile-only {
  display: none;
}

@media (max-width: 68rem) {
  .site-header__inner {
    min-height: 4.25rem;
    justify-content: space-between;
  }

  .site-header__brand {
    font-size: 1rem;
  }

  .site-header__logo {
    width: 2rem;
    height: 2rem;
    flex-basis: 2rem;
  }

  .site-header__toggle {
    display: inline-flex;
    width: 2.75rem;
    min-width: 2.75rem;
    height: 2.75rem;
    min-height: 2.75rem;
    flex: 0 0 2.75rem;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 0.27rem;
    padding: 0;
    border: 1px solid var(--color-line);
    border-radius: var(--radius-md);
    background: rgba(255, 255, 255, 0.82);
  }

  .site-header__toggle:hover {
    transform: none;
    border-color: var(--color-sky);
    background: #fff;
  }

  .site-header__toggle-line {
    display: block;
    width: 1.15rem;
    height: 2px;
    border-radius: 999px;
    background: var(--color-ink);
    transition: transform var(--transition-fast), opacity var(--transition-fast), background-color var(--transition-fast);
  }

  .site-header__toggle[aria-expanded="true"] .site-header__toggle-line {
    background: var(--color-primary);
  }

  .site-header__toggle[aria-expanded="true"] .site-header__toggle-line:nth-child(1) {
    transform: translateY(0.4rem) rotate(45deg);
  }

  .site-header__toggle[aria-expanded="true"] .site-header__toggle-line:nth-child(2) {
    opacity: 0;
  }

  .site-header__toggle[aria-expanded="true"] .site-header__toggle-line:nth-child(3) {
    transform: translateY(-0.4rem) rotate(-45deg);
  }

  .site-header__actions {
    display: none;
  }

  .site-header__nav {
    position: absolute;
    top: calc(100% + 0.5rem);
    right: max(1rem, calc((100vw - var(--container-width)) / 2));
    left: max(1rem, calc((100vw - var(--container-width)) / 2));
    display: grid;
    max-height: min(32rem, calc(100vh - 5.5rem));
    overflow: auto;
    visibility: hidden;
    gap: var(--space-4);
    padding: var(--space-4);
    border: var(--border-glass);
    border-radius: var(--radius-lg);
    background: rgba(252, 254, 255, 0.96);
    box-shadow: var(--shadow-card);
    opacity: 0;
    pointer-events: none;
    transform: translateY(-0.5rem);
    transition: opacity var(--transition-base), transform var(--transition-base), visibility var(--transition-base);
  }

  .site-header__nav.is-open {
    visibility: visible;
    opacity: 1;
    pointer-events: auto;
    transform: translateY(0);
  }

  .site-header__nav-list {
    display: grid;
    gap: 0.15rem;
  }

  .site-header__nav-list a {
    width: 100%;
    min-height: 2.75rem;
    padding: 0.55rem 0.65rem;
    border-radius: var(--radius-sm);
  }

  .site-header__nav-list a:hover,
  .site-header__nav-list a[aria-current="page"] {
    background: color-mix(in srgb, var(--color-celestine) 13%, white);
  }

  .site-header__nav-list a::after {
    display: none;
  }

  .site-header__nav-mobile-only,
  .site-header__mobile-action {
    display: block;
  }

  .site-header__mobile-action {
    padding-top: var(--space-3);
    border-top: var(--border-default);
  }

  .site-header__mobile-action .button {
    width: 100%;
  }
}

@media (max-width: 25rem) {
  .site-header__brand-full {
    display: none;
  }

  .site-header__brand-short {
    display: inline;
  }
}

@media (prefers-reduced-motion: reduce) {
  .site-header,
  .site-header__nav,
  .site-header__toggle-line {
    transition: none;
  }
}