/* Keep heading text aligned with the page; put the control in the gutter. */
.foldable-heading {
  position: relative;
}

.heading-toggle {
  position: absolute;
  inset-inline-start: -1.35em;
  top: 0;
  width: 1.25em;
  height: 1.5em;
  padding: 0;
  border: 0;
  background: transparent;
  color: inherit;
  font: inherit;
  line-height: 1;
  cursor: pointer;
  opacity: 0.6;
}

.heading-toggle:hover,
.heading-toggle:focus-visible {
  opacity: 1;
}

.heading-toggle:focus-visible {
  outline: 2px solid currentColor;
  outline-offset: 2px;
  border-radius: 2px;
}

.heading-toggle span {
  display: inline-block;
  width: 0;
  height: 0;
  border-top: 0.23em solid transparent;
  border-bottom: 0.23em solid transparent;
  border-left: 0.35em solid currentColor;
  transform: rotate(90deg);
}

.heading-toggle[aria-expanded="false"] span {
  transform: none;
}

/* Avoid adding a layout box or changing paragraph/heading margin collapse. */
.foldable-section {
  display: contents;
}

.foldable-section[hidden] {
  display: none !important;
}

/* Narrow pages have no spare gutter for an outside control. */
@media (max-width: 600px) {
  .heading-toggle {
    position: static;
    margin-inline-end: 0.15em;
    vertical-align: baseline;
  }
}

@media print {
  .heading-toggle {
    display: none !important;
  }

  .foldable-section[hidden] {
    display: contents !important;
  }
}