@import url('https://fonts.googleapis.com/css2?family=Noto+Serif+SC:wght@400;600;700&display=swap');

/* Prevent horizontal scroll from full-width header trick */
html { overflow-x: hidden; }

/* Site header - fixed at top, always full viewport width */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.55rem 1.5rem;
  background: #fff;
  border-bottom: 1px solid #e8e5e0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 0.82rem;
  z-index: 100;
}
.site-header a { color: #2563eb; text-decoration: none; }
.site-header a:hover { text-decoration: underline; }
.site-header .site-name { color: #1a1a1a; font-weight: 600; font-size: 0.85rem; }
.site-header .site-name:hover { color: #2563eb; }
.site-header .site-nav { display: flex; gap: 0.8rem; align-items: center; }
.site-header .nav-sep { color: #ddd; font-size: 0.7rem; user-select: none; }
.site-header .nav-pipe { color: #ddd; margin: 0 0.1rem; font-size: 0.75rem; user-select: none; }
.site-header a.nav-active { color: #1a1a1a !important; font-weight: 700; }

/* Consistent spacer below fixed header - all pages get the same top offset */
.site-header-spacer { height: 3.5rem; }

/* Site footer nav */
.site-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem 1.5rem;
  margin: 3rem auto 0;
  max-width: 800px;
  border-top: 1px solid #e8e5e0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 0.82rem;
}
.site-footer a { color: #2563eb; text-decoration: none; }
.site-footer a:hover { text-decoration: underline; }
.site-footer .placeholder { visibility: hidden; }

/* i18n: bilingual visibility toggle */
html[lang="zh-CN"] .en { display: none !important; }
html[lang="en"] .zh { display: none !important; }

/* Language toggle button */
.lang-toggle {
  background: none;
  border: 1.5px solid #d0d0d0;
  border-radius: 4px;
  padding: 1px 8px;
  font-size: 0.75rem;
  font-weight: 600;
  color: #666;
  cursor: pointer;
  margin-left: 0.3rem;
  transition: border-color 0.2s, color 0.2s;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.4;
}
.lang-toggle:hover {
  border-color: #2563eb;
  color: #2563eb;
}

/* Hide header in print mode */
@media print {
  .site-header, .site-header-spacer, .site-footer { display: none !important; }
}