/* A single glass surface lives outside the scroll-clipped sidebar. Its shell
   stays painted while metadata and the spring's destination change. */
.nav-preview {
  --site-accent-fg-color: var(--reading-accent);
  --site-accent-fg-color--transparent: var(--nav-hover);
  --site-border-color: var(--reading-rule);
  position: fixed;
  top: 0;
  left: 0;
  z-index: 45;
  width: 440px;
  height: min(480px, 62vh);
  visibility: hidden;
  pointer-events: none;
  color: var(--site-default-fg-color);
  font-size: .875rem;
  line-height: 1.5;
  transition: visibility 0s linear 180ms;
  contain: layout style;
  will-change: transform;
}
.nav-preview.is-visible { visibility: visible; pointer-events: auto; transition-delay: 0s; }
.nav-preview__surface {
  height: 100%;
  border: 1px solid var(--nav-divider);
  border-radius: var(--site-radius-lg);
  overflow: hidden;
  background: color-mix(in srgb, var(--nav-panel-bg) 96%, transparent);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  box-shadow: var(--nav-panel-shadow);
  opacity: 0;
  transform: translateX(-6px);
  transform-origin: left 32px;
  transition: opacity 150ms ease, transform 180ms cubic-bezier(.4,0,1,1);
}
.nav-preview.is-visible .nav-preview__surface {
  opacity: 1;
  transform: translateX(0);
  transition: opacity 160ms ease, transform 220ms cubic-bezier(.16,1,.3,1);
}
.nav-preview__content {
  position: relative; border-radius: inherit; overflow: hidden;
}
.nav-preview__content { height: 100%; display: flex; flex-direction: column; min-height: 0; }
.nav-preview__head { flex: 0 0 auto; padding: 24px 24px 12px; border-bottom: 0; }
.nav-preview__eyebrow, .nav-preview__label { color: var(--site-default-fg-color--light); font-size: .75rem; font-weight: 500; letter-spacing: 0; }
.nav-preview__eyebrow { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; margin-bottom: 7px; }
.nav-preview__title { margin: 0; font: inherit; font-size: 1.12rem; font-weight: 600; line-height: 1.45; overflow-wrap: anywhere; display: -webkit-box; -webkit-line-clamp: 3; -webkit-box-orient: vertical; overflow: hidden; }
.nav-preview__title a { color: inherit; text-decoration: none; }
.nav-preview__title a:hover { color: var(--site-accent-fg-color); }
.nav-preview__meta { display: flex; flex-wrap: wrap; gap: 5px 10px; margin-top: 10px; color: var(--site-default-fg-color--light); font-size: .75rem; max-height: 3.4em; overflow: hidden; }
.nav-preview__tag { color: var(--site-accent-fg-color); }
.nav-preview__body { flex: 1 1 auto; min-height: 0; overflow-y: auto; overscroll-behavior: contain; scrollbar-gutter: stable; padding: 12px 18px 24px 24px; }
.nav-preview__description { margin: 0 0 20px; font-size: .875rem; line-height: 1.7; overflow-wrap: anywhere; }
.nav-preview__label { margin-bottom: 9px; }
.nav-preview__toc { display: flex; flex-direction: column; gap: 2px; }
.nav-preview__toc a, .nav-preview__folder {
  display: block; text-align: left; padding: 7px 10px; margin-left: -10px;
  border: 0; border-radius: var(--site-nav-radius); color: inherit; background: transparent;
  font: inherit; line-height: 1.5; text-decoration: none; overflow-wrap: anywhere;
  cursor: pointer; transition: color 120ms ease, background-color 120ms ease;
}
.nav-preview__toc a[data-level="3"] { margin-left: 4px; padding-left: 10px; color: var(--site-default-fg-color--light); }
.nav-preview__toc a:hover, .nav-preview__folder:hover { color: var(--site-accent-fg-color); background: var(--site-accent-fg-color--transparent); }
.nav-preview__folder { display: flex; gap: 12px; align-items: baseline; justify-content: space-between; }
.nav-preview__count { flex-shrink: 0; color: var(--site-default-fg-color--light); font-size: .75rem; }
.nav-preview__empty, .nav-preview__status { margin: 0 0 14px; color: var(--site-default-fg-color--light); }
.nav-preview__retry { font: inherit; color: var(--site-accent-fg-color); background: var(--site-accent-fg-color--transparent); border: 1px solid var(--site-border-color); border-radius: 8px; padding: 6px 12px; cursor: pointer; }
.nav-preview__skeleton { display: flex; flex-direction: column; gap: 14px; padding-top: 6px; animation: navPreviewPulse 1.5s ease-in-out infinite alternate; }
.nav-preview__skeleton i { display: block; height: 10px; width: 83%; border-radius: 5px; background: color-mix(in srgb, var(--site-default-fg-color) 10%, transparent); }
.nav-preview__skeleton i:nth-child(2) { width: 65%; margin-bottom: 22px; }
.nav-preview__skeleton i:nth-child(2n+3) { width: 58%; margin-left: 14px; }
.nav-preview :focus-visible { outline: 2px solid var(--site-accent-fg-color); outline-offset: 2px; }
.nav-preview__body:focus-visible { outline-offset: -3px; border-radius: 6px; }
@keyframes navPreviewPulse { from { opacity: .45; } to { opacity: .95; } }
@supports not (backdrop-filter: blur(1px)) { .nav-preview__surface { background: var(--nav-panel-bg); } }
@media (prefers-reduced-motion: reduce) {
  .nav-preview, .nav-preview__surface, .nav-preview.is-visible .nav-preview__surface { transition: none; }
  .nav-preview__skeleton { animation: none; }
}
@media (max-width: 1024px), (hover: none), (pointer: coarse) { .nav-preview { display: none; } }
@media print { .nav-preview { display: none; } }

/* Breadcrumb ancestors open below the header and share the navigation shell. */
.breadcrumb-preview { z-index: 99; }
.breadcrumb-preview .nav-preview__surface { transform: translateY(-6px); transform-origin: top left; }
.breadcrumb-preview.is-visible .nav-preview__surface { transform: translateY(0); }
.breadcrumb-preview .nav-preview__head { padding: 20px 24px 8px; }
.breadcrumb-preview .nav-preview__directory a.nav-preview__folder { display: flex; }
.breadcrumb-preview .nav-preview__directory [aria-current] { color: var(--reading-accent); font-weight: 600; }
.site-breadcrumbs a.site-nav__preview-target { color: var(--reading-accent); text-decoration: underline; text-underline-offset: .2em; }

/* Chapter content uses the same shell, with a compact reading measure. */
.toc-preview[data-side="left"] .nav-preview__surface { transform: translateX(6px); transform-origin: right 32px; }
.toc-preview[data-side="left"].is-visible .nav-preview__surface { transform: translateX(0); }
.toc-preview__article { font-size: 14px; line-height: 1.8; overflow-wrap: anywhere; }
.toc-preview__article > :first-child { margin-top: 0; }
.toc-preview__article > :last-child { margin-bottom: 0; }
.toc-preview__article :is(h2, h3, h4, h5, h6) { margin: 1.5em 0 .65em; font-size: 15px; line-height: 1.5; font-weight: 600; }
.toc-preview__article p { margin: 0 0 1em; }
.toc-preview__article :is(ul, ol) { padding-left: 1.4em; margin-block: .7em 1em; }
.toc-preview__article li + li { margin-top: .3em; }
.toc-preview__article a { color: var(--reading-accent); text-underline-offset: .2em; }
.toc-preview__article pre { max-width: 100%; overflow: auto; padding: 14px; margin-block: 1em; border: 1px solid var(--reading-rule); border-radius: 8px; background: var(--reading-surface); font-size: 12px; line-height: 1.7; }
.toc-preview__article .syn-header { font-size: 11px; margin-bottom: 10px; color: var(--site-default-fg-color--light); }
.toc-preview__article :not(pre) > code { font-size: .9em; background: var(--reading-surface); padding: .1em .25em; border-radius: 3px; }
.toc-preview__article blockquote { margin: 1em 0; padding: 0 12px; border-left: 2px solid var(--reading-rule); }
.toc-preview__article table { display: block; max-width: 100%; overflow-x: auto; border-collapse: collapse; font-size: 13px; }
.toc-preview__article :is(th, td) { padding: 8px 10px; border-bottom: 1px solid var(--reading-rule); min-width: 6em; }
.toc-preview__article th { background: var(--reading-surface); }
.toc-preview__article img, .toc-preview__article svg { max-width: 100%; height: auto; }
.toc-preview__article figure { margin: 1em 0; }
.toc-preview .toc-preview__article .math-tex { transition: none; }
.toc-preview .toc-preview__article .toc-preview__math-pending { opacity: 1; font-family: monospace; }
.toc-preview__diagram { margin-block: 1em; padding: 12px; border: 1px solid var(--reading-rule); border-radius: 8px; background: var(--reading-surface); }
.toc-preview__diagram p { color: var(--site-default-fg-color--light); font-size: 13px; margin-bottom: 8px; }
@media (max-width: 1359px) { .toc-preview { display: none; } }