/* Page shell: top bar, sidebar with block index tabs A–Z, the reading desk grid with its margin rail, the phone drawer and the search dialog. */

body::before {
  content: "";
  position: fixed;
  inset: 0 0 auto;
  height: env(safe-area-inset-top, 0px);
  z-index: 60;
  background: var(--bg);
}

/* ---------- top bar ---------- */
.nb-top {
  position: sticky;
  top: env(safe-area-inset-top, 0px);
  z-index: 50;
  display: flex;
  align-items: center;
  gap: var(--s3);
  height: var(--top-h);
  padding-left: var(--gutter-l);
  padding-right: var(--gutter-r);
  border-bottom: 1px solid var(--rule);
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  -webkit-backdrop-filter: saturate(1.4) blur(10px);
  backdrop-filter: saturate(1.4) blur(10px);
}
.nb-menu { display: none; margin-left: -6px; }

.nb-brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
  color: var(--ink);
  font: 600 var(--t-ui) / 1 var(--font-ui);
  letter-spacing: -0.005em;
}
.nb-brand:hover { text-decoration: none; }
.nb-brand-mark {
  display: grid;
  place-items: center;
  width: 28px;
  height: 28px;
  border-radius: 7px;
  background: var(--ink);
  color: var(--bg);
  font: 600 17px / 1 var(--font-read);
  font-variation-settings: "opsz" 36;
}
.nb-brand-sub { color: var(--ink-3); font-weight: 500; }

.nb-crumbs {
  display: flex;
  align-items: center;
  gap: 6px;
  min-width: 0;
  margin-left: var(--s4);
  color: var(--ink-3);
  font-size: var(--t-sm);
  white-space: nowrap;
  overflow: hidden;
}
.nb-crumbs a { color: var(--ink-2); }
.nb-crumbs a:hover { color: var(--ink); }
.nb-crumbs .sep { color: var(--ink-4); }
.nb-crumbs .last { color: var(--ink); font-weight: 500; overflow: hidden; text-overflow: ellipsis; }

.nb-top-actions { display: flex; align-items: center; gap: var(--s1); margin-left: auto; }

.nb-search-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--s2);
  width: 15rem;
  height: 34px;
  padding: 0 6px 0 10px;
  border: 1px solid var(--rule-2);
  border-radius: var(--r-sm);
  background: var(--surface);
  color: var(--ink-3);
  font-size: var(--t-sm);
  cursor: pointer;
}
.nb-search-btn:hover { border-color: var(--ink-4); color: var(--ink-2); }
.nb-search-btn span { flex: 1; text-align: left; }
.nb-search-btn svg { width: 16px; height: 16px; fill: none; stroke: currentColor; stroke-width: 1.6; stroke-linecap: round; }

/* ---------- frame ---------- */
.nb-frame {
  display: grid;
  grid-template-columns: var(--side-w) minmax(0, 1fr);
  min-height: calc(100vh - var(--top-h));
  /* the sidebar column keeps its paper and hairline down to the end of a long page */
  background: linear-gradient(to right, var(--bg-side) calc(var(--side-w) - 1px), var(--rule) calc(var(--side-w) - 1px) var(--side-w), transparent var(--side-w));
}

.nb-side {
  position: sticky;
  top: calc(env(safe-area-inset-top, 0px) + var(--top-h));
  align-self: start;
  height: calc(100vh - var(--top-h) - env(safe-area-inset-top, 0px));
  overflow-y: auto;
  overscroll-behavior: contain;
  padding: var(--s5) var(--s3) var(--s6);
  scrollbar-width: thin;
  scrollbar-color: var(--rule-2) transparent;
}

.nb-side-nav { display: grid; gap: 2px; }
.nb-side-link {
  display: flex;
  align-items: center;
  gap: 10px;
  height: 32px;
  padding: 0 10px;
  border-radius: var(--r-sm);
  color: var(--ink-2);
  font-size: var(--t-ui);
}
.nb-side-link svg { width: 16px; height: 16px; fill: none; stroke: currentColor; stroke-width: 1.6; stroke-linecap: round; stroke-linejoin: round; color: var(--ink-3); }
.nb-side-link:hover { background: var(--hover); color: var(--ink); text-decoration: none; }
.nb-side-link[aria-current="page"] { background: var(--active); color: var(--ink); font-weight: 550; }

.nb-side-label {
  margin: var(--s5) 10px var(--s2);
  font: 600 var(--t-xs) / 1 var(--font-ui);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-3);
}

/* index tabs: one square tab per block letter, like the alphabet edge of a notebook */
.nb-tabs, .nb-tree { list-style: none; margin: 0; padding: 0; }
.nb-tabs { display: grid; gap: 2px; }
.nb-tab {
  display: grid;
  grid-template-columns: 26px minmax(0, 1fr) auto;
  align-items: center;
  gap: 10px;
  min-height: 36px;
  padding: 4px 10px 4px 6px;
  border-radius: var(--r-sm);
  color: var(--ink-2);
}
.nb-tab:hover { background: var(--hover); color: var(--ink); text-decoration: none; }
.nb-tab-letter {
  display: grid;
  place-items: center;
  width: 26px;
  height: 26px;
  border: 1px solid var(--rule-2);
  border-radius: 6px;
  background: var(--surface);
  color: var(--ink);
  font: 600 14px / 1 var(--font-read);
  font-variation-settings: "opsz" 24;
}
.nb-tab-name { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.nb-tab-count { color: var(--ink-3); font-size: var(--t-xs); font-variant-numeric: tabular-nums; }
.nb-tab.is-empty { color: var(--ink-3); }
.nb-tab.is-empty .nb-tab-letter { color: var(--ink-3); background: transparent; border-color: var(--rule); }
.nb-tab[aria-current="page"], .nb-tab.is-open { color: var(--ink); font-weight: 550; }
.nb-tab[aria-current="page"] .nb-tab-letter, .nb-tab.is-open .nb-tab-letter { background: var(--ink); border-color: var(--ink); color: var(--bg); }
.nb-tab[aria-current="page"] { background: var(--active); }

.nb-tree { margin: 2px 0 var(--s3) 19px; padding-left: 12px; border-left: 1px solid var(--rule); }
.nb-tree-sec {
  margin: var(--s3) 0 2px;
  padding: 0 8px;
  color: var(--ink-3);
  font: 600 var(--t-xs) / 1.3 var(--font-ui);
}
.nb-tree-sec:first-child { margin-top: var(--s2); }
.nb-tree a {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 8px;
  align-items: baseline;
  padding: 5px 8px;
  border-radius: var(--r-sm);
  color: var(--ink-2);
  font-size: var(--t-sm);
  line-height: 1.35;
}
.nb-tree a:hover { background: var(--hover); color: var(--ink); text-decoration: none; }
.nb-tree a[aria-current="page"] { background: var(--active); color: var(--ink); font-weight: 550; }
.nb-tree .code { color: var(--ink-3); font-size: var(--t-xs); font-variant-numeric: tabular-nums; font-weight: 600; }
.nb-tree .t { overflow: hidden; text-overflow: ellipsis; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; }

.nb-side-foot {
  margin: var(--s6) 10px 0;
  color: var(--ink-3);
  font-size: var(--t-xs);
  line-height: 1.5;
}

/* ---------- main area ---------- */
.nb-main {
  min-width: 0;
  padding-block: var(--s7) var(--s9);
  padding-inline: clamp(16px, 3.2vw, 48px);
}
.nb-main:focus { outline: none; }

/* wide pages: home, block, sources, components */
.nb-page { width: 100%; max-width: 68rem; margin: 0 auto; }

/* document desk: reading column + margin rail */
.nb-desk {
  display: grid;
  grid-template-columns: minmax(0, var(--read-w)) var(--rail-w);
  gap: var(--desk-gap);
  justify-content: center;
  max-width: var(--wide-w);
  margin: 0 auto;
}
.nb-desk > article { min-width: 0; }
.nb-rail { position: relative; }
.nb-rail-in {
  position: sticky;
  top: calc(var(--top-h) + var(--s6));
  display: grid;
  gap: var(--s6);
  max-height: calc(100vh - var(--top-h) - var(--s7));
  overflow-y: auto;
  padding-bottom: var(--s4);
  scrollbar-width: thin;
}
.nb-rail h2 { margin-bottom: var(--s2); }
.nb-toc { display: grid; gap: 1px; margin: 0; padding: 0; list-style: none; border-left: 1px solid var(--rule); }
.nb-toc a {
  display: block;
  margin-left: -1px;
  padding: 4px 0 4px 12px;
  border-left: 2px solid transparent;
  color: var(--ink-3);
  font-size: var(--t-sm);
  line-height: 1.4;
}
.nb-toc a.lvl3 { padding-left: 24px; }
.nb-toc a:hover { color: var(--ink); text-decoration: none; }
.nb-toc a.is-active { border-left-color: var(--ink); color: var(--ink); }

/* wide documents (tables and charts first): one column as wide as text + rail, running text keeps the reading measure */
.nb-desk.is-wide { grid-template-columns: minmax(0, var(--wide-w)); }
.nb-desk.is-wide .nb-rail { display: none; }

.nb-foot {
  margin-top: var(--s8);
  padding-top: var(--s4);
  border-top: 1px solid var(--rule);
  color: var(--ink-3);
  font-size: var(--t-xs);
}

/* ---------- search dialog ---------- */
.nb-search {
  position: fixed;
  inset: 0;
  z-index: 80;
  display: grid;
  align-items: start;
  justify-items: center;
  padding: 12vh var(--gutter-r) 0 var(--gutter-l);
  background: rgba(10, 10, 9, 0.32);
}
.nb-search-panel {
  display: grid;
  grid-template-rows: auto minmax(0, 1fr) auto;
  width: min(42rem, 100%);
  max-height: 72vh;
  border-radius: var(--r-lg);
  background: var(--surface);
  box-shadow: var(--shadow-pop);
  overflow: hidden;
}
.nb-search-head { display: flex; align-items: center; gap: var(--s3); padding: 0 var(--s4); border-bottom: 1px solid var(--rule); }
.nb-search-head svg { width: 18px; height: 18px; fill: none; stroke: var(--ink-3); stroke-width: 1.6; stroke-linecap: round; flex-shrink: 0; }
.nb-search-head input {
  flex: 1;
  min-width: 0;
  height: 54px;
  border: 0;
  background: transparent;
  color: var(--ink);
  font: 400 1.0625rem / 1 var(--font-ui);
  outline: none;
}
.nb-search-head input::placeholder { color: var(--ink-4); }
.nb-search-head input::-webkit-search-cancel-button { -webkit-appearance: none; appearance: none; }
.nb-search-list { overflow-y: auto; padding: var(--s2); }
.nb-search-empty { padding: var(--s6) var(--s4); color: var(--ink-3); text-align: center; }
.nb-hit {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 4px var(--s3);
  padding: 10px var(--s3);
  border-radius: var(--r);
  color: var(--ink);
}
.nb-hit:hover, .nb-hit[aria-selected="true"] { background: var(--active); text-decoration: none; }
.nb-hit .nb-id { grid-row: span 2; align-self: start; margin-top: 2px; }
.nb-hit-title { font-weight: 550; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.nb-hit-title .h { color: var(--ink-3); font-weight: 450; }
.nb-hit-snip { color: var(--ink-2); font-size: var(--t-sm); line-height: 1.45; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; }
.nb-search-foot { display: flex; gap: var(--s4); flex-wrap: wrap; padding: 10px var(--s4); border-top: 1px solid var(--rule); color: var(--ink-3); font-size: var(--t-xs); }

/* ---------- responsive ---------- */
@media (max-width: 1180px) {
  .nb-desk { grid-template-columns: minmax(0, var(--read-w)); }
  .nb-rail { display: none; }
}

@media (max-width: 960px) {
  .nb-menu { display: inline-grid; }
  .nb-crumbs { display: none; }
  .nb-frame { grid-template-columns: minmax(0, 1fr); background: none; }
  .nb-side {
    border-right: 1px solid var(--rule);
    background: var(--bg-side);
    position: fixed;
    top: 0;
    bottom: 0;
    left: 0;
    z-index: 70;
    width: min(20rem, 86vw);
    height: auto;
    padding-top: calc(var(--s5) + env(safe-area-inset-top, 0px));
    padding-left: max(var(--s3), env(safe-area-inset-left, 0px));
    transform: translateX(-102%);
    transition: transform 0.22s ease;
    box-shadow: var(--shadow-pop);
  }
  .nb-side-open .nb-side { transform: none; }
  .nb-backdrop { position: fixed; inset: 0; z-index: 65; background: rgba(10, 10, 9, 0.32); }
  .nb-main { padding-block: var(--s6) var(--s8); }
}

@media (max-width: 640px) {
  .nb-search-btn { width: 36px; padding: 0; justify-content: center; border-color: transparent; background: transparent; }
  .nb-search-btn span, .nb-search-btn kbd { display: none; }
  .nb-brand-sub { display: none; }
  .nb-main { padding-inline: 0; padding-left: var(--gutter-l); padding-right: var(--gutter-r); }
  .nb-search { padding-top: 8px; }
  .nb-search-panel { max-height: 86vh; }
}