/* Base layer: reset, page background, typography defaults, links, focus, small utilities shared by every page. */

*, *::before, *::after { box-sizing: border-box; }
[hidden] { display: none !important; }

html {
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
  scroll-padding-top: calc(var(--top-h) + 24px);
}

body {
  margin: 0;
  min-height: 100vh;
  background: var(--bg);
  color: var(--ink);
  font: 400 var(--t-ui) / var(--lh-ui) var(--font-ui);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  font-kerning: normal;
}

h1, h2, h3, h4, h5 { margin: 0; text-wrap: balance; }
p, figure, blockquote, dl, dd { margin: 0; }
img, svg { max-width: 100%; }
svg { display: block; }
button { font: inherit; color: inherit; }
table { border-collapse: collapse; }

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; text-decoration-thickness: 1px; text-underline-offset: 3px; }

:focus { outline: none; }
:focus-visible {
  outline: 1.5px solid var(--focus);
  outline-offset: 2px;
  border-radius: var(--r-sm);
}

::selection { background: var(--accent-wash); }

mark {
  background: var(--mark);
  color: inherit;
  border-radius: 3px;
  padding: 0 1px;
  margin: 0 -1px;
}

kbd {
  display: inline-block;
  min-width: 1.5em;
  padding: 1px 5px;
  border: 1px solid var(--rule-2);
  border-bottom-width: 2px;
  border-radius: 5px;
  background: var(--surface);
  color: var(--ink-3);
  font: 500 var(--t-xs) / 1.3 var(--font-ui);
  text-align: center;
}

code, .nb-code {
  font-family: var(--font-code);
  font-size: 0.86em;
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

/* utilities */
.nb-vh {
  position: absolute !important;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}
.nb-num { font-variant-numeric: tabular-nums; }
.nb-muted { color: var(--ink-3); }
.nb-nowrap { white-space: nowrap; }

.nb-eyebrow {
  font: 600 var(--t-xs) / 1.2 var(--font-ui);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-3);
}

.nb-skip {
  position: absolute;
  left: var(--gutter-l);
  top: -100px;
  z-index: 100;
  padding: var(--s2) var(--s3);
  border-radius: var(--r-sm);
  background: var(--ink);
  color: var(--bg);
}
.nb-skip:focus-visible { top: var(--s2); }

/* sample ribbon: every page built from fixtures says so */
.nb-sample {
  display: flex;
  gap: var(--s2);
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  padding-block: 7px;
  padding-left: var(--gutter-l);
  padding-right: var(--gutter-r);
  background: var(--part-wash);
  color: var(--part-ink);
  font: 500 var(--t-sm) / 1.35 var(--font-ui);
  text-align: center;
}
.nb-sample b { font-weight: 650; }

/* code ID chip: block letter + section codes and source IDs */
.nb-id {
  display: inline-flex;
  align-items: center;
  padding: 1px 7px;
  border-radius: var(--r-sm);
  background: var(--sunken);
  color: var(--ink-2);
  font: 600 var(--t-xs) / 1.6 var(--font-ui);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.02em;
  white-space: nowrap;
}
a.nb-id:hover { background: var(--accent-wash); color: var(--accent-ink); text-decoration: none; }

/* external link with a small arrow */
.nb-ext::after {
  content: "";
  display: inline-block;
  width: 0.62em;
  height: 0.62em;
  margin-left: 0.22em;
  vertical-align: 0.06em;
  background: currentColor;
  -webkit-mask: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 10 10'%3E%3Cpath d='M3 1h6v6M9 1 1 9' fill='none' stroke='black' stroke-width='1.6'/%3E%3C/svg%3E") center / contain no-repeat;
  mask: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 10 10'%3E%3Cpath d='M3 1h6v6M9 1 1 9' fill='none' stroke='black' stroke-width='1.6'/%3E%3C/svg%3E") center / contain no-repeat;
  opacity: 0.7;
}

/* buttons */
.nb-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--s2);
  height: 32px;
  padding: 0 var(--s3);
  border: 1px solid var(--rule-2);
  border-radius: var(--r-sm);
  background: var(--surface);
  color: var(--ink-2);
  font: 500 var(--t-sm) / 1 var(--font-ui);
  cursor: pointer;
}
.nb-btn:hover { background: var(--hover); color: var(--ink); }
.nb-btn[aria-pressed="true"] { background: var(--active); color: var(--ink); border-color: var(--ink-4); }

.nb-iconbtn {
  display: inline-grid;
  place-items: center;
  width: 36px;
  height: 36px;
  border: 0;
  border-radius: var(--r-sm);
  background: transparent;
  color: var(--ink-2);
  cursor: pointer;
}
.nb-iconbtn:hover { background: var(--hover); color: var(--ink); }
.nb-iconbtn svg { width: 18px; height: 18px; fill: none; stroke: currentColor; stroke-width: 1.6; stroke-linecap: round; stroke-linejoin: round; }