/* 经典官网的风格切换入口，不改动原页面样式。 */
.theme-bridge {
  position: fixed; right: 20px; bottom: 20px; z-index: 350;
  display: flex; gap: 4px; padding: 4px;
  border: 1px solid var(--color-rule-strong); border-radius: 999px;
  background: var(--color-paper); color: var(--color-ink-soft);
  font: 500 14px/1.2 var(--font-body);
  box-shadow: 0 6px 26px var(--color-overlay);
}
.theme-bridge a, .theme-bridge span { display: flex; align-items: center; justify-content: center; gap: 8px; min-height: 44px; padding: 12px 18px; border-radius: 999px; text-decoration: none; }
.theme-bridge a { color: var(--color-ink-soft); transition: background .2s, color .2s; }
.theme-bridge a i { width: 14px; height: 14px; border-radius: 50%; background: radial-gradient(circle at 34% 30%, #fffbea, #ffd57e 45%, #f2a14a); box-shadow: 0 0 10px rgba(255, 190, 100, .6); }
.theme-bridge span { background: var(--color-paper-4); color: var(--color-ink); }
.theme-bridge a:hover { background: var(--color-paper-3); color: var(--color-ink); }
.theme-bridge a:focus-visible { outline: 2px solid var(--color-focus); outline-offset: 3px; }
.theme-bridge a:active { background: var(--color-paper-4); }

.theme-veil {
  position: fixed; inset: 0; z-index: 3000; pointer-events: none;
  background: radial-gradient(90% 60% at 80% 10%, rgba(255, 220, 160, .55), transparent 60%), linear-gradient(180deg, #a6cbe5, #d6e8f2 55%, #edf3f6);
  clip-path: circle(0 at var(--vx, 50%) var(--vy, 50%));
}
html.is-leaving .theme-veil { clip-path: circle(150vmax at var(--vx, 50%) var(--vy, 50%)); transition: clip-path .62s cubic-bezier(.7, 0, .2, 1); pointer-events: auto; }
html.veil-in .theme-veil {
  clip-path: none; opacity: 1;
  background: repeating-linear-gradient(0deg, rgba(47, 224, 232, .05) 0 1px, transparent 1px 4px), radial-gradient(120% 80% at 50% 40%, #0f171b, #070a0c);
}
html.veil-in.veil-out .theme-veil { opacity: 0; transition: opacity .7s cubic-bezier(.2, .7, .1, 1); }

@media (max-width: 640px) {
  .theme-bridge { right: 12px; bottom: calc(12px + env(safe-area-inset-bottom)); padding: 3px; }
  .theme-bridge span { display: none; }
  .theme-bridge a { min-height: 40px; padding: 8px 14px; font-size: 13px; }
}
@media (prefers-reduced-motion: reduce) { .theme-veil { display: none; } }