/* Shared chrome (theme CSS variables are defined per-page) */
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font-body);
  background: var(--color-base);
  color: var(--color-ink);
  font-size: 17px;
  line-height: 1.65;
}
h1, h2, h3, .font-display { font-family: var(--font-display); }
a:focus-visible, button:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 3px;
}
#site-header {
  background: transparent;
  border-bottom: 1px solid transparent;
  transition: background .25s ease, border-color .25s ease, backdrop-filter .25s ease;
}
#site-header.is-scrolled {
  background: color-mix(in srgb, var(--color-base) 92%, transparent);
  border-bottom-color: var(--color-border);
  backdrop-filter: blur(8px);
}
#mobile-nav {
  display: none;
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
}
#mobile-nav.is-open { display: block; }
.btn-primary {
  display: inline-flex; align-items: center; justify-content: center;
  background: var(--color-primary); color: #fff;
  padding: .75rem 1.35rem; border-radius: 4px;
  font-weight: 600; font-size: .95rem; text-decoration: none;
  box-shadow: 0 2px 8px color-mix(in srgb, var(--color-primary) 35%, transparent);
  transition: transform .15s ease, box-shadow .15s ease, background .15s ease;
}
.btn-primary:hover { transform: translateY(-2px); background: #b82430; }
.btn-secondary {
  display: inline-flex; align-items: center; justify-content: center;
  background: transparent; color: var(--color-ink);
  padding: .75rem 1.25rem; border-radius: 4px;
  border: 1px solid var(--color-border); text-decoration: none; font-weight: 500;
  transition: border-color .15s ease, transform .15s ease;
}
.btn-secondary:hover { border-color: var(--color-muted); transform: translateY(-1px); }
.nav-link {
  color: var(--color-muted); text-decoration: none; font-size: .9rem; font-weight: 500;
  padding: .25rem 0; border-bottom: 2px solid transparent;
}
.nav-link:hover, .nav-link[aria-current="page"] {
  color: var(--color-ink); border-bottom-color: var(--color-primary);
}
.panel {
  background: var(--color-panel);
  border: 1px solid var(--color-border);
  border-radius: 6px;
  box-shadow: 0 8px 24px rgba(0,0,0,.22);
  transition: transform .22s ease, border-color .22s ease, box-shadow .22s ease;
}
.panel-accent { border-left: 3px solid var(--color-primary); }
.panel-hover:hover {
  transform: translateY(-3px);
  border-color: color-mix(in srgb, var(--color-accent) 42%, var(--color-border));
  box-shadow:
    0 16px 36px rgba(0,0,0,.32),
    0 0 0 1px color-mix(in srgb, var(--color-accent) 16%, transparent);
}
.eyebrow {
  font-size: .72rem; font-weight: 600; letter-spacing: .12em;
  text-transform: uppercase; color: var(--color-accent);
}
.sep-constellation {
  display: flex; align-items: center; justify-content: center; gap: .75rem;
  color: var(--color-border); padding: 2rem 0 .5rem;
}
.sep-line { flex: 1; max-width: 120px; height: 1px; background: linear-gradient(90deg, transparent, var(--color-border), transparent); }
.page-intro {
  padding: 7rem 0 3rem;
  background: linear-gradient(165deg, var(--color-surface) 0%, var(--color-base) 70%);
  border-bottom: 1px solid var(--color-border);
}
.breadcrumb { font-size: .85rem; color: var(--color-muted); margin-bottom: 1rem; }
.breadcrumb a { color: var(--color-muted); text-decoration: none; }
.breadcrumb a:hover { color: var(--color-ink); }
.compare-table { width: 100%; border-collapse: collapse; font-size: .92rem; }
.compare-table th, .compare-table td {
  padding: .85rem 1rem; text-align: left;
  border-bottom: 1px solid var(--color-border);
}
.compare-table th {
  color: var(--color-muted); font-weight: 500; font-size: .8rem;
  text-transform: uppercase; letter-spacing: .04em;
}
.timeline { border-left: 2px solid var(--color-border); margin-left: .5rem; padding-left: 1.5rem; }
.timeline-item { position: relative; padding-bottom: 2rem; }
.timeline-item::before {
  content: ""; position: absolute; left: -1.7rem; top: .35rem;
  width: 10px; height: 10px; border-radius: 50%;
  background: var(--color-primary); box-shadow: 0 0 0 3px var(--color-base);
}
.float-dl {
  position: fixed; right: 1.25rem; bottom: 1.25rem; z-index: 40;
  box-shadow: 0 8px 28px rgba(0,0,0,.4);
}
#lightbox {
  position: fixed; inset: 0; z-index: 60; display: none;
  align-items: center; justify-content: center;
  background: rgba(8,10,14,.88); padding: 1.5rem;
}
#lightbox.is-open { display: flex; }
#lightbox img { max-width: min(1100px, 94vw); max-height: 88vh; border-radius: 4px; }
#lightbox-close {
  position: absolute; top: 1rem; right: 1rem;
  width: 44px; height: 44px; border: 1px solid var(--color-border);
  background: var(--color-surface); color: var(--color-ink);
  border-radius: 4px; font-size: 1.4rem; cursor: pointer;
}
.acc-btn {
  width: 100%; text-align: left; background: transparent; border: 0;
  color: var(--color-ink); padding: 1.1rem 1.2rem; cursor: pointer;
  display: flex; justify-content: space-between; align-items: center; gap: 1rem;
  font-family: var(--font-body); font-size: 1.02rem; font-weight: 500;
}
.acc-panel { padding: 0 1.2rem 1.15rem; color: var(--color-muted); }
[data-acc-item] { border-bottom: 1px solid var(--color-border); }
.step-num {
  display: inline-flex; align-items: center; justify-content: center;
  width: 1.75rem; height: 1.75rem; border-radius: 4px;
  background: var(--color-primary); color: #fff; font-size: .85rem; font-weight: 600;
}
.toc a { color: var(--color-accent); text-decoration: none; }
.toc a:hover { text-decoration: underline; }
body.nav-open { overflow: hidden; }
.site-footer {
  background: #0B0F14;
  border-top: 1px solid var(--color-border);
  padding: 3.5rem 0 2.5rem;
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}

/* Language switcher dropdown */
.lang-switch { position: relative; }
.lang-switch-btn {
  display: inline-flex; align-items: center; gap: .35rem;
  background: transparent; color: var(--color-muted);
  border: 1px solid var(--color-border); border-radius: 6px;
  padding: .35rem .55rem; font-size: .78rem; font-weight: 600;
  font-family: var(--font-body); cursor: pointer; letter-spacing: .02em;
}
.lang-switch-btn:hover { color: var(--color-ink); border-color: var(--color-muted); }
.lang-switch-menu {
  position: absolute; top: calc(100% + 6px); right: 0; z-index: 70;
  min-width: 10.5rem; margin: 0; padding: .35rem;
  list-style: none; background: var(--color-surface);
  border: 1px solid var(--color-border); border-radius: 8px;
  box-shadow: 0 12px 32px rgba(0,0,0,.4);
}
.lang-switch-menu[hidden] { display: none !important; }
.lang-switch-menu a {
  display: block; padding: .55rem .7rem; border-radius: 6px;
  color: var(--color-ink); text-decoration: none; font-size: .85rem;
}
.lang-switch-menu a:hover,
.lang-switch-menu a[aria-current="true"] {
  background: color-mix(in srgb, var(--color-accent) 12%, transparent);
}
html[lang="zh-CN"] .nav-link,
html.lang-zh .nav-link { letter-spacing: .08em; }
html[lang="ru"] .btn-primary,
html.lang-ru .btn-primary { padding-left: 1.55rem; padding-right: 1.55rem; }
html[dir="rtl"] .float-dl { right: auto; left: 1.25rem; }
html[dir="rtl"] .lang-switch-menu { right: auto; left: 0; }
html[dir="rtl"] .compare-table th,
html[dir="rtl"] .compare-table td { text-align: right; }
html[dir="rtl"] .acc-btn { text-align: right; }