.fd-header {
  position: sticky;
  top: 0;
  z-index: 40;
  background-color: rgba(249, 250, 249, 0.96);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(222, 223, 227, 0.8);
}

.fd-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: var(--space-3);
  padding-bottom: var(--space-3);
  gap: var(--space-4);
}

.fd-header__brand {
  display: flex;
  align-items: center;
  min-width: 0;
}

.fd-header__logo-link {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  color: var(--color-text);
}

.fd-header__logo-mark {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: radial-gradient(circle at 30% 20%, #e2f0eb 0, #e2f0eb 40%, #4c8f7a 41%, #3b7161 100%);
  box-shadow: var(--shadow-soft);
}

.fd-header__site-name {
  font-family: var(--font-serif);
  font-size: var(--font-size-lg);
  letter-spacing: 0.04em;
  text-transform: uppercase;
  white-space: nowrap;
}

/* Navigation */
.fd-header__nav {
  margin-left: auto;
}

.fd-header__nav-list {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}

.fd-header__nav-item {
  list-style: none;
}

.fd-header__nav-link {
  position: relative;
  display: inline-flex;
  align-items: center;
  font-size: var(--font-size-sm);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--gray-700);
  padding: 0.35rem 0;
}

.fd-header__nav-link::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: -0.25rem;
  height: 2px;
  border-radius: 999px;
  background: linear-gradient(90deg, #4c8f7a, #e2f0eb);
  transform-origin: center;
  transform: scaleX(0);
  transition: transform var(--transition-base);
}

.fd-header__nav-link:hover::after,
.fd-header__nav-link:focus-visible::after {
  transform: scaleX(1);
}

.fd-header__nav-item--highlight .fd-header__nav-link {
  color: var(--color-primary);
}

/* Mobile toggle */
.fd-header__toggle {
  display: none;
  position: relative;
  width: 40px;
  height: 40px;
  border-radius: 999px;
  border: 1px solid rgba(76, 143, 122, 0.3);
  justify-content: center;
  align-items: center;
  background-color: #ffffff;
  cursor: pointer;
}

.fd-header__toggle-bar {
  position: absolute;
  width: 18px;
  height: 2px;
  border-radius: 999px;
  background-color: var(--gray-800);
  transition: transform var(--transition-base), opacity var(--transition-base), top var(--transition-base), bottom var(--transition-base);
}

.fd-header__toggle-bar:nth-child(1) {
  top: 13px;
}

.fd-header__toggle-bar:nth-child(2) {
  top: 19px;
}

.fd-header__toggle-bar:nth-child(3) {
  bottom: 13px;
}

.fd-header__toggle[aria-expanded="true"] .fd-header__toggle-bar:nth-child(1) {
  top: 19px;
  transform: rotate(45deg);
}

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

.fd-header__toggle[aria-expanded="true"] .fd-header__toggle-bar:nth-child(3) {
  bottom: 19px;
  transform: rotate(-45deg);
}

/* Mobile layout */
@media (max-width: 768px) {
  .fd-header__inner {
    padding-top: var(--space-3);
    padding-bottom: var(--space-3);
  }

  .fd-header__toggle {
    display: inline-flex;
  }

  .fd-header__nav {
    position: absolute;
    inset-inline: 0;
    top: 100%;
    background-color: rgba(249, 250, 249, 0.98);
    border-bottom: 1px solid rgba(222, 223, 227, 0.95);
    box-shadow: var(--shadow-soft);
    transform-origin: top;
  }

  .fd-header__nav-list {
    flex-direction: column;
    align-items: flex-start;
    padding: var(--space-4);
    gap: var(--space-3);
  }

  /* Progressive enhancement: visible by default, JS will hide on load */
  .fd-header__nav[hidden] {
    display: none !important;
  }

  .fd-header__nav-link {
    width: 100%;
    padding: 0.4rem 0;
  }
}

@media (min-width: 769px) {
  .fd-header__nav {
    position: static;
  }
}