:root {
  --site-ink: #152333;
  --site-muted: #5c6a78;
  --site-blue: #1769aa;
  --site-blue-dark: #0c4e83;
  --site-surface: #ffffff;
  --site-tint: #edf4f8;
  --site-border: #d8e3ea;
  --site-shadow: 0 12px 28px rgba(19, 48, 70, 0.11);
  --site-radius: 16px;
}

* { box-sizing: border-box; }

html, body { margin: 0; min-height: 100%; }

body {
  color: var(--site-ink);
  background: var(--site-tint);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont,
    "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
}

.site-header {
  position: relative;
  z-index: 100;
  min-height: 72px;
  background: rgba(255, 255, 255, 0.97);
  border-bottom: 1px solid var(--site-border);
}

.site-nav {
  width: min(1240px, calc(100% - 40px));
  min-height: 72px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.site-brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  flex: 0 0 auto;
  min-width: 0;
}

.site-brand img { display: block; max-width: 100%; object-fit: contain; }
.site-brand .brand-dde { width: 114px; height: 48px; }
.site-brand .brand-geomorphology { width: 154px; height: 48px; }

.desktop-nav {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 6px;
}

.language-switch {
  flex: 0 0 auto;
  padding: 8px 10px;
  color: var(--site-blue-dark);
  background: #fff;
  border: 1px solid #b7cfdf;
  border-radius: 8px;
  cursor: pointer;
  font: inherit;
  font-size: 0.88rem;
  font-weight: 750;
  line-height: 1.2;
}

.language-switch:hover,
.language-switch:focus-visible {
  color: #fff;
  background: var(--site-blue-dark);
  border-color: var(--site-blue-dark);
  outline: none;
}

.mobile-menu-panel .language-switch {
  width: 100%;
  text-align: left;
  border: 0;
  border-radius: 8px;
}

.site-nav a { color: inherit; text-decoration: none; }

.desktop-nav a {
  padding: 10px 12px;
  border-radius: 8px;
  color: #304250;
  font-size: 0.94rem;
  font-weight: 650;
  white-space: nowrap;
}

.desktop-nav a:hover,
.desktop-nav a:focus-visible,
.desktop-nav a[aria-current="page"] {
  color: var(--site-blue-dark);
  background: #e7f2fa;
  outline: none;
}

.mobile-menu { display: none; position: relative; }
.mobile-menu summary {
  list-style: none;
  cursor: pointer;
  color: var(--site-blue-dark);
  border: 1px solid #b7cfdf;
  border-radius: 8px;
  padding: 8px 12px;
  font-weight: 700;
}
.mobile-menu summary::-webkit-details-marker { display: none; }
.mobile-menu-panel {
  position: absolute;
  top: calc(100% + 10px);
  right: 0;
  width: min(280px, calc(100vw - 32px));
  display: grid;
  gap: 4px;
  padding: 10px;
  background: #fff;
  border: 1px solid var(--site-border);
  border-radius: 12px;
  box-shadow: var(--site-shadow);
}
.mobile-menu-panel a {
  padding: 11px 12px;
  border-radius: 8px;
  font-weight: 650;
}
.mobile-menu-panel a:hover,
.mobile-menu-panel a:focus-visible,
.mobile-menu-panel a[aria-current="page"] {
  color: var(--site-blue-dark);
  background: #e7f2fa;
  outline: none;
}

.site-footer {
  min-height: 48px;
  display: grid;
  place-items: center;
  padding: 12px 20px;
  color: #526270;
  background: #fff;
  border-top: 1px solid var(--site-border);
  font-size: 0.82rem;
  text-align: center;
}

@media (max-width: 820px) {
  .site-header, .site-nav { min-height: 64px; }
  .site-nav { width: min(100% - 24px, 620px); gap: 12px; }
  .site-brand { gap: 6px; }
  .site-brand .brand-dde { width: 82px; height: 40px; }
  .site-brand .brand-geomorphology { width: 98px; height: 40px; }
  .desktop-nav { display: none; }
  .mobile-menu { display: block; }
}

@media (max-width: 390px) {
  .site-brand .brand-dde { width: 72px; }
  .site-brand .brand-geomorphology { width: 86px; }
  .mobile-menu summary { padding: 7px 10px; font-size: 0.9rem; }
}