.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 50;
  height: var(--header-h);
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  padding: 0 2.2rem;
  transition: background 0.4s var(--ease), border-color 0.4s var(--ease), backdrop-filter 0.4s var(--ease);
  border-bottom: 1px solid transparent;
}

.site-header.is-scrolled {
  background: rgba(7, 7, 7, 0.78);
  backdrop-filter: blur(16px);
  border-bottom-color: var(--line);
}

.brand {
  display: flex;
  align-items: center;
  justify-self: start;
}

.brand__mark {
  display: block;
  width: 42px;
  height: 42px;
  object-fit: contain;
}

.brand__full {
  display: none;
}

.nav {
  display: flex;
  gap: 2rem;
  align-items: center;
}

.nav a {
  font-size: 0.78rem;
  letter-spacing: 0.2em;
  color: var(--text);
  position: relative;
  padding: 0.3rem 0;
}

.nav a::after {
  content: "";
  position: absolute;
  left: 50%;
  bottom: 0;
  width: 0;
  height: 1px;
  background: var(--gold);
  transition: width 0.35s var(--ease), left 0.35s var(--ease);
}

.nav a:hover::after,
.nav a:focus-visible::after,
.nav a.is-active::after {
  width: 100%;
  left: 0;
}

.header-tools {
  justify-self: end;
  display: flex;
  align-items: center;
  gap: 1.1rem;
}

.lang-in-nav {
  display: none;
}

.lang {
  display: flex;
  align-items: center;
  gap: 0.15rem;
  border: 1px solid var(--line);
  padding: 0.18rem;
}

.lang button {
  min-width: 2.1rem;
  height: 1.85rem;
  font-size: 0.68rem;
  letter-spacing: 0.08em;
  color: var(--muted);
  padding: 0 0.4rem;
}

.lang button[aria-pressed="true"] {
  background: var(--gold-grad);
  color: #16110a;
}

.menu-toggle {
  display: none;
  width: 42px;
  height: 42px;
  position: relative;
}

.menu-toggle span,
.menu-toggle span::before,
.menu-toggle span::after {
  position: absolute;
  left: 10px;
  width: 22px;
  height: 1px;
  background: var(--gold-1);
  transition: transform 0.3s var(--ease), opacity 0.3s;
}

.menu-toggle span {
  top: 50%;
}

.menu-toggle span::before,
.menu-toggle span::after {
  content: "";
  left: 0;
}

.menu-toggle span::before {
  top: -7px;
}

.menu-toggle span::after {
  top: 7px;
}

.site-header.is-open .menu-toggle span {
  background: transparent;
}

.site-header.is-open .menu-toggle span::before {
  top: 0;
  transform: rotate(45deg);
}

.site-header.is-open .menu-toggle span::after {
  top: 0;
  transform: rotate(-45deg);
}

@media (max-width: 1100px) {
  .site-header {
    grid-template-columns: 1fr auto;
    padding: 0 1.1rem;
  }

  .brand__mark {
    width: 36px;
    height: 36px;
  }

  .menu-toggle {
    display: block;
  }

  .nav {
    position: fixed;
    inset: var(--header-h) 0 0 0;
    background: rgba(7, 7, 7, 0.96);
    flex-direction: column;
    justify-content: center;
    gap: 2.2rem;
    transform: translateY(-120%);
    opacity: 0;
    pointer-events: none;
    transition: transform 0.5s var(--ease), opacity 0.5s var(--ease);
  }

  .site-header.is-open .nav {
    transform: none;
    opacity: 1;
    pointer-events: auto;
  }

  .nav a {
    font-size: 1.4rem;
    letter-spacing: 0.28em;
    font-family: var(--font-display-zh);
  }

  html[data-lang="en"] .nav a {
    font-family: var(--font-display-en);
  }

  html[data-lang="zh-Hans"] .nav a {
    font-family: var(--font-display-sc);
  }
}