/* On a phone, code and its output wrap instead of scrolling sideways:
   the printed summary of a model has lines of about 120 characters. */
@media (max-width: 575.98px) {
  pre {
    white-space: pre-wrap;
    overflow-wrap: anywhere;
    hyphens: none;
  }
}

/* The articles as a book (see extra.js): section numbers, the chapter panel,
   previous / next chapter. Colours come from Bootstrap's variables, so light
   and dark mode both work. */
.section-number {
  margin-right: 0.5em;
  color: var(--bs-secondary-color);
  font-variant-numeric: tabular-nums;
}
.book-panel h2 { margin-top: 1.5rem; font-size: 1.25rem; }
.book-panel ol { list-style: none; margin: 0; padding: 0; }
.book-panel .book-part {
  margin: 0.9rem 0 0.2rem 0.5rem;
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--bs-secondary-color);
}
.book-panel .book-row { display: flex; align-items: flex-start; }
.book-panel a {
  display: flex;
  flex: 1 1 auto;
  gap: 0.5em;
  padding: 0.25rem 0.5rem;
  margin-bottom: 2px;
  border-radius: var(--bs-border-radius);
  color: inherit;
  text-decoration: none;
  line-height: 1.3;
}
.book-panel a:hover, .book-panel a:focus {
  background-color: rgba(var(--bs-primary-rgb), 0.1);
}
.book-panel .book-num {
  flex: 0 0 auto;
  min-width: 1.2em;
  color: var(--bs-secondary-color);
  font-variant-numeric: tabular-nums;
}
.book-panel .book-chapter.current > .book-row > a {
  font-weight: 600;
  color: var(--bs-link-color);
  background-color: rgba(var(--bs-primary-rgb), 0.08);
}
.book-panel code { font-size: 0.9em; padding: 0; background: none; color: inherit; }
.book-panel .book-sections { margin-left: 0.75rem; font-size: 0.9em; }
.book-panel .book-sections .book-sections { margin-left: 1rem; }
.book-panel .book-sections .book-num { min-width: 2em; }
.book-panel .book-sections .book-sections .book-num { min-width: 2.8em; }
.book-panel .book-sections a.active {
  background-color: rgba(var(--bs-body-color-rgb), 0.1);
  font-weight: 600;
}
.book-panel .book-unfold {
  flex: 0 0 auto;
  width: 1.6rem;
  height: 1.6rem;
  margin-top: 0.1rem;
  border: 0;
  border-radius: var(--bs-border-radius);
  background: none;
  color: var(--bs-secondary-color);
}
.book-panel .book-unfold::before {
  content: "";
  display: inline-block;
  border: solid currentColor;
  border-width: 0 1.5px 1.5px 0;
  padding: 2.5px;
  transform: rotate(-45deg);
  transition: transform 0.15s;
}
.book-panel .book-unfold[aria-expanded="true"]::before { transform: rotate(45deg); }
.book-panel .book-unfold:hover { background-color: rgba(var(--bs-primary-rgb), 0.1); }

/* Wide screens: the panel stays in view in the sidebar. */
@media (min-width: 768px) {
  .book-panel-side {
    position: sticky;
    top: 56px;
    max-height: calc(100vh - 56px - 1rem);
    overflow-y: auto;
  }
  .book-panel-phone { display: none; }
}
/* Phones: a collapsed "Chapters" box below the title, no sidebar. */
@media (max-width: 767.98px) {
  .row > aside.book-aside { display: none; }
  .book-panel-phone {
    margin: 0 0 1.5rem;
    border: 1px solid var(--bs-border-color);
    border-radius: var(--bs-border-radius);
    background-color: rgba(var(--bs-body-color-rgb), 0.04);
  }
  .book-panel-phone > summary { padding: 0.5rem 0.75rem; font-weight: 600; }
  .book-panel-phone .book-panel { padding: 0 0.5rem 0.5rem; }
  .book-panel-phone .book-panel h2 { display: none; }
}

.book-pager {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin: 3rem 0 1rem;
  padding-top: 1rem;
  border-top: 1px solid var(--bs-border-color);
}
.book-pager a {
  display: flex;
  flex-direction: column;
  max-width: 48%;
  text-decoration: none;
}
.book-pager .book-pager-next { margin-left: auto; text-align: right; }
.book-pager-label { font-size: 0.85em; color: var(--bs-secondary-color); }
.book-pager-title { font-weight: 600; }