.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(255, 255, 255, 0.86);
  backdrop-filter: blur(16px);
  transition:
    transform 220ms ease,
    border-color var(--ease),
    box-shadow var(--ease),
    background var(--ease);
  will-change: transform;
}

.site-header.is-scrolled,
.site-header.is-menu-open {
  border-bottom: 1px solid var(--line);
  box-shadow: 0 10px 24px rgba(16, 24, 40, 0.04);
}

.site-header.is-hidden {
  transform: translateY(calc(-100% - 0.75rem));
}

.site-header__inner {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
  min-height: var(--header-height);
}

.site-mark {
  font-size: 0.82rem;
  font-weight: 800;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  white-space: nowrap;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  flex-wrap: nowrap;
}

.site-nav a {
  position: relative;
  padding: 0.2rem 0;
  color: var(--muted);
  font-size: 0.95rem;
  transition: color var(--ease), background var(--ease), box-shadow var(--ease);
}

.site-nav a::after {
  content: "";
  position: absolute;
  right: 0;
  bottom: -0.15rem;
  left: 0;
  height: 1px;
  background: currentColor;
  transform: scaleX(0);
  transform-origin: left;
  transition: transform var(--ease);
}

.site-nav a:hover,
.site-nav a[aria-current="true"] {
  color: var(--text);
}

.site-nav a:hover::after,
.site-nav a[aria-current="true"]::after {
  transform: scaleX(1);
}

.site-menu-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  width: 3rem;
  height: 3rem;
  padding: 0;
  border: 1px solid var(--line-strong);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.92);
  color: var(--text);
  cursor: pointer;
  transition:
    border-color var(--ease),
    box-shadow var(--ease),
    transform var(--ease);
}

.site-menu-toggle:hover {
  border-color: var(--accent);
  box-shadow: 0 10px 24px rgba(16, 24, 40, 0.08);
  transform: translateY(-1px);
}

.site-menu-toggle__icon {
  position: relative;
  width: 1rem;
  height: 0.8rem;
}

.site-menu-toggle__icon span {
  position: absolute;
  left: 0;
  width: 100%;
  height: 2px;
  border-radius: 999px;
  background: currentColor;
  transform-origin: center;
  transition: transform var(--ease), opacity var(--ease), top var(--ease);
}

.site-menu-toggle__icon span:nth-child(1) {
  top: 0;
}

.site-menu-toggle__icon span:nth-child(2) {
  top: calc(50% - 1px);
}

.site-menu-toggle__icon span:nth-child(3) {
  top: calc(100% - 2px);
}

.site-header.is-menu-open .site-menu-toggle__icon span:nth-child(1) {
  top: calc(50% - 1px);
  transform: rotate(45deg);
}

.site-header.is-menu-open .site-menu-toggle__icon span:nth-child(2) {
  opacity: 0;
}

.site-header.is-menu-open .site-menu-toggle__icon span:nth-child(3) {
  top: calc(50% - 1px);
  transform: rotate(-45deg);
}

@media (max-width: 860px) {
  .site-header__inner {
    display: grid;
    grid-template-columns: minmax(0, 1fr) auto;
    gap: 0.75rem;
    padding: 0.8rem 0;
  }

  .site-menu-toggle {
    display: inline-flex;
  }

  .site-nav {
    position: absolute;
    top: calc(100% - 0.15rem);
    right: 0;
    left: 0;
    display: grid;
    gap: 0.25rem;
    padding: 0.65rem;
    border: 1px solid var(--line);
    border-radius: 1.25rem;
    background: rgba(255, 255, 255, 0.98);
    box-shadow: 0 20px 44px rgba(16, 24, 40, 0.12);
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transform: translateY(-0.75rem);
    transition:
      opacity var(--ease),
      transform var(--ease),
      visibility 0s linear var(--ease);
  }

  .site-header.is-menu-open .site-nav {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
    transform: translateY(0);
    transition-delay: 0s;
  }

  .site-nav a {
    display: block;
    padding: 0.8rem 0.95rem;
    border-radius: 0.9rem;
    font-size: 1rem;
  }

  .site-nav a::after {
    display: none;
  }

  .site-nav a:hover,
  .site-nav a[aria-current="true"] {
    background: var(--bg-soft);
    color: var(--text);
  }

  .site-nav a[aria-current="true"] {
    box-shadow: inset 0 0 0 1px var(--line);
  }
}