/* 中文站顶栏的跨页面视觉契约。
   首页保留独立 DOM，普通页面走 default layout；两边的实际像素由这里统一收口。 */
:root {
  --site-nav-height: 56px;
  --site-nav-bg: rgb(250, 250, 249);
  --site-nav-bg-dark: rgb(26, 25, 24);
  --site-nav-gold-border: rgba(201, 169, 110, 0.46);
  --site-nav-gold-soft: rgba(201, 169, 110, 0.16);
  --site-nav-font: 'Cormorant Garamond', 'Noto Serif SC', 'Source Han Serif SC',
    'Source Han Serif CN', 'Songti SC', 'STSong', 'SimSun', 'Hiragino Mincho ProN', serif;
}

.site-shell-nav {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: 1000;
  width: 100%;
  height: var(--site-nav-height);
  min-height: var(--site-nav-height);
  box-sizing: border-box;
  background: var(--site-nav-bg);
  border-bottom: 1px solid var(--color-border);
  -webkit-backdrop-filter: none;
  backdrop-filter: none;
  font-family: var(--site-nav-font);
  font-size: 16px;
  font-weight: 400;
  line-height: normal;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .site-shell-nav { background: var(--site-nav-bg-dark); }
}
:root[data-theme="light"] .site-shell-nav { background: var(--site-nav-bg); }
:root[data-theme="dark"] .site-shell-nav { background: var(--site-nav-bg-dark); }

.topbar.site-shell-nav,
.site-shell-nav > .nav-inner {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 1.4rem;
  width: 100%;
  margin: 0;
  padding: 0 clamp(16px, 3.4vw, 44px);
  box-sizing: border-box;
  font-size: 16px;
  line-height: normal;
}
.topbar.site-shell-nav { height: var(--site-nav-height); min-height: var(--site-nav-height); }
.site-shell-nav > .nav-inner { height: 100%; min-height: 0; }

.site-shell-nav .brand,
.site-shell-nav .nav-brand {
  display: inline-flex;
  align-items: baseline;
  justify-self: start;
  gap: 0.5rem;
  margin: 0;
  padding: 0;
  color: var(--color-ink);
  font-family: var(--site-nav-font);
  font-size: 1.34rem;
  font-weight: 600;
  line-height: 1.4;
  letter-spacing: 0.14em;
  text-decoration: none;
  white-space: nowrap;
}

.site-shell-nav .brand__zh { font: inherit; color: inherit; }
.site-shell-nav .brand__la,
.site-shell-nav .nav-brand::after {
  color: var(--color-highlight);
  font-family: var(--site-nav-font);
  font-size: 0.74rem;
  font-weight: 400;
  line-height: 1.4;
  letter-spacing: 0.32em;
  text-transform: uppercase;
}
.site-shell-nav .nav-brand::after { margin-left: 0; }

.site-shell-nav .mainnav,
.site-shell-nav .nav-links {
  display: flex;
  align-items: center;
  justify-self: center;
  gap: 1.4rem;
  margin: 0;
  padding: 0;
  line-height: normal;
}

.site-shell-nav .mainnav a,
.site-shell-nav .nav-links > li:not(.nav-link-home):not(.nav-settings) > a {
  position: relative;
  display: block;
  margin: 0;
  padding: 0.2rem 0;
  color: var(--color-text);
  font-family: var(--site-nav-font);
  font-size: 0.98rem;
  font-weight: 500;
  line-height: 1.4;
  letter-spacing: 0.06em;
  text-decoration: none;
  white-space: nowrap;
}

.site-shell-nav .mainnav a::after,
.site-shell-nav .nav-links > li:not(.nav-link-home):not(.nav-settings) > a::after {
  content: "";
  position: absolute;
  right: 100%;
  bottom: -2px;
  left: 0;
  height: 1px;
  background: var(--color-highlight);
  transition: right 0.3s ease;
}
.site-shell-nav .mainnav a:hover::after,
.site-shell-nav .mainnav a:focus-visible::after,
.site-shell-nav .nav-links > li:not(.nav-link-home):not(.nav-settings) > a:hover::after,
.site-shell-nav .nav-links > li:not(.nav-link-home):not(.nav-settings) > a:focus-visible::after { right: 0; }

.site-shell-nav .util,
.site-shell-nav .nav-right-box,
.site-shell-nav .nav-controls {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.site-shell-nav .util,
.site-shell-nav .nav-right-box { justify-self: end; }

.site-shell-nav #nav-search-btn,
.site-shell-nav .js-theme,
.site-shell-nav .nav-theme-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 34px;
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  color: var(--color-muted);
  background: transparent;
  border: 1px solid var(--color-border);
  border-radius: 50%;
  font-family: inherit;
  font-size: 1rem;
  font-weight: 400;
  line-height: 1;
}
.site-shell-nav #nav-search-btn .nav-search-text { display: none; }
.site-shell-nav #nav-search-btn svg { width: 16px; height: 16px; }

.site-shell-nav .en,
.site-shell-nav .lang-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  margin: 0;
  padding: 0.32rem 0.66rem;
  box-sizing: border-box;
  color: var(--color-highlight);
  background: transparent;
  border: 1px solid var(--site-nav-gold-border);
  border-radius: var(--radius-pill);
  font-family: var(--site-nav-font);
  font-size: 0.86rem;
  font-weight: 600;
  line-height: normal;
  letter-spacing: 0.14em;
  text-decoration: none;
  white-space: nowrap;
}
.site-shell-nav .en b { color: inherit; font-weight: inherit; }

.site-shell-nav #auth-slot { display: flex; align-items: center; }
.site-shell-nav #auth-slot .sa-login-btn {
  margin: 0;
  padding: 0.3rem 0.6rem;
  color: var(--color-muted);
  background: transparent;
  border: 1px solid var(--site-nav-gold-soft);
  border-radius: var(--radius-pill);
  font-family: inherit;
  font-size: 0.8rem;
  font-weight: 600;
  line-height: normal;
  letter-spacing: 0.04em;
}

@media (max-width: 1080px) {
  .topbar.site-shell-nav .mainnav { display: none; }
}

@media (max-width: 960px) {
  body > .site-shell-nav { height: auto; min-height: var(--site-nav-height); }
  body > .site-shell-nav > .nav-inner {
    height: auto;
    min-height: var(--site-nav-height);
    padding: 0.6rem 1.2rem;
    gap: 0.5rem;
  }
  body > .site-shell-nav .nav-links { display: none; }
  body > .site-shell-nav .nav-links.open { display: flex; }
}