.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  height: var(--nav-h);
  background: rgba(246, 247, 249, 0.92);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid transparent;
  transition: border-color 0.25s ease, background 0.25s ease;
}

.site-header.is-scrolled {
  border-bottom-color: var(--line);
  background: rgba(255, 255, 255, 0.96);
}

.site-header__inner {
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.85rem;
  flex-shrink: 0;
}

.brand img {
  height: 3.25rem;
  width: auto;
}

.brand__name {
  font-family: var(--font-body);
  font-size: clamp(1.35rem, 2.4vw, 1.75rem);
  font-weight: 600;
  letter-spacing: 0.08em;
  line-height: 1;
  text-transform: uppercase;
  color: var(--ink);
}

.nav {
  display: flex;
  align-items: center;
  gap: 1.45rem;
}

.nav a {
  font-size: 0.875rem;
  font-weight: 500;
  letter-spacing: 0.02em;
  color: var(--ink-soft);
  position: relative;
}

.nav a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -0.35rem;
  width: 100%;
  height: 1px;
  background: var(--steel);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.25s ease;
}

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

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

.lang-switch {
  position: relative;
  margin-left: 0.15rem;
  flex-shrink: 0;
}

.lang-switch__btn {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  min-height: 2.25rem;
  padding: 0.35rem 0.7rem 0.35rem 0.55rem;
  border: 1px solid var(--line);
  border-radius: 0.55rem;
  background: linear-gradient(180deg, #fff 0%, var(--mist) 100%);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  cursor: pointer;
  transition: border-color 0.2s ease, box-shadow 0.2s ease, background 0.2s ease;
}

.lang-switch__btn:hover,
.lang-switch.is-open .lang-switch__btn {
  border-color: var(--steel);
  box-shadow: 0 6px 18px rgba(61, 111, 150, 0.12);
  background: var(--white);
}

.lang-switch__btn:focus-visible {
  outline: 2px solid var(--steel);
  outline-offset: 2px;
}

.lang-switch__icon {
  width: 1.05rem;
  height: 1.05rem;
  color: var(--steel-deep);
  flex-shrink: 0;
}

.lang-switch__current {
  line-height: 1;
  white-space: nowrap;
}

.lang-switch__chevron {
  width: 0.7rem;
  height: 0.7rem;
  color: var(--muted);
  transition: transform 0.2s ease;
}

.lang-switch.is-open .lang-switch__chevron {
  transform: rotate(180deg);
}

.lang-switch__menu {
  position: absolute;
  top: calc(100% + 0.45rem);
  right: 0;
  z-index: 60;
  min-width: 11.5rem;
  margin: 0;
  padding: 0.35rem;
  list-style: none;
  border: 1px solid var(--line);
  border-radius: 0.75rem;
  background: rgba(255, 255, 255, 0.98);
  box-shadow: 0 18px 40px rgba(27, 36, 48, 0.14);
  backdrop-filter: blur(10px);
}

.lang-switch__menu[hidden] {
  display: none;
}

.lang-switch__option {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  padding: 0.55rem 0.65rem;
  border-radius: 0.5rem;
  color: var(--ink-soft);
  font-size: 0.8125rem;
  font-weight: 500;
  text-decoration: none;
  transition: background 0.15s ease, color 0.15s ease;
}

.lang-switch__option::after {
  display: none !important;
}

.lang-switch__option:hover {
  background: var(--mist);
  color: var(--ink);
}

.lang-switch__option--current {
  background: rgba(106, 158, 196, 0.12);
  color: var(--ink);
  font-weight: 600;
  pointer-events: none;
}

.lang-switch__badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 1.65rem;
  height: 1.65rem;
  border-radius: 999px;
  background: linear-gradient(145deg, var(--steel-deep), var(--steel));
  color: var(--white);
  font-size: 0.62rem;
  font-weight: 700;
  letter-spacing: 0.02em;
  flex-shrink: 0;
}

.lang-switch__label {
  flex: 1;
  line-height: 1.2;
}

.lang-switch__check {
  width: 0.55rem;
  height: 0.55rem;
  border-radius: 999px;
  background: transparent;
  flex-shrink: 0;
}

.lang-switch__option--current .lang-switch__check {
  background: var(--steel-deep);
  box-shadow: 0 0 0 3px rgba(61, 111, 150, 0.18);
}

.nav__cta {
  padding: 0.55rem 1.1rem;
  border: 1px solid var(--steel-deep);
  border-radius: var(--radius);
  background: var(--steel-deep);
  color: var(--white) !important;
}

.nav__cta::after {
  display: none !important;
}

.nav__cta:hover {
  background: var(--ink);
  border-color: var(--ink);
  color: var(--white) !important;
}

.nav-toggle {
  display: none;
  width: 2.5rem;
  height: 2.5rem;
  border: 1px solid var(--line);
  background: var(--white);
  cursor: pointer;
  padding: 0;
}

.nav-toggle span {
  display: block;
  width: 1.1rem;
  height: 1px;
  margin: 0.3rem auto;
  background: var(--ink);
}

.site-footer {
  background: var(--paper);
  border-top: 3px solid var(--steel);
  padding: 3.5rem 0 2rem;
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.35fr 1fr 1fr 1fr 1fr;
  gap: 2rem;
  margin-bottom: 2.5rem;
}

.footer-brand__lockup {
  display: inline-flex;
  align-items: center;
  gap: 0.65rem;
  margin-bottom: 1rem;
  color: var(--ink);
  text-decoration: none;
}

.footer-brand__lockup img {
  height: 2.25rem;
  width: auto;
  padding: 0;
  background: none;
  border-radius: 0;
}

.footer-brand__lockup span {
  font-family: var(--font-body);
  font-size: 1.15rem;
  font-weight: 600;
  letter-spacing: 0.04em;
}

.footer-brand p {
  color: var(--muted);
  font-size: 0.92rem;
  max-width: 18rem;
  margin-bottom: 1rem;
}

.footer-brand a {
  color: var(--steel-deep);
  font-weight: 600;
}

.footer-col h4 {
  font-family: var(--font-body);
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin: 0 0 1rem;
  padding: 0;
}

.footer-col a {
  display: block;
  color: var(--ink-soft);
  font-size: 0.92rem;
  margin-bottom: 0.55rem;
}

.footer-col a:hover {
  color: var(--steel-deep);
}

.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 0.75rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.8rem;
}

/* Footer WeChat QR block
   位于 .footer-brand 列内，卡片固定宽度约 118px，
   在 1.35fr 品牌列及移动端单列布局中均不会撑破列宽 */
.footer-wechat {
  margin-top: 0.25rem;
}

.footer-wechat h4 {
  font-family: var(--font-body);
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin: 0 0 1rem;
}

.footer-wechat__card {
  display: inline-block;
  background: var(--white);
  padding: 6px;
  border-radius: 8px;
  border: 1px solid var(--line);
  box-shadow: var(--shadow);
  transition: transform 0.25s ease, box-shadow 0.25s ease;
}

.footer-wechat__card:hover {
  transform: translateY(-3px);
  box-shadow: 0 20px 44px rgba(61, 111, 150, 0.2);
}

.footer-wechat__card img {
  display: block;
  width: 104px;
  height: 104px;
  object-fit: cover;
  border-radius: 4px;
}

.footer-wechat .footer-wechat__caption {
  margin: 0.6rem 0 0;
  max-width: none;
  font-size: 0.8rem;
  color: var(--muted);
}

.split {
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  gap: 3rem;
  align-items: center;
}

.split--top {
  align-items: start;
}

@media (max-width: 1100px) {
  .footer-grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 980px) {
  .nav {
    position: fixed;
    inset: var(--nav-h) 0 auto 0;
    display: none;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 1rem 1.25rem 1.25rem;
    background: var(--white);
    border-bottom: 1px solid var(--line);
  }

  .nav.is-open {
    display: flex;
  }

  .nav a {
    padding: 0.85rem 0;
    border-bottom: 1px solid var(--line);
  }

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

  .lang-switch {
    width: 100%;
    margin: 0.5rem 0 0;
    padding: 0.75rem 0;
    border-bottom: 1px solid var(--line);
  }

  .lang-switch__btn {
    width: 100%;
    justify-content: flex-start;
    border-radius: var(--radius);
  }

  .lang-switch__menu {
    position: static;
    margin-top: 0.5rem;
    min-width: 0;
    width: 100%;
    box-shadow: none;
  }

  .lang-switch__option {
    padding: 0.7rem 0.65rem;
    border-bottom: 0;
  }

  .nav__cta {
    margin-top: 0.75rem;
    text-align: center;
  }

  .nav-toggle {
    display: inline-block;
  }

  .footer-grid,
  .split {
    grid-template-columns: 1fr;
  }
}