/* Sidebar: keep the top-level section headings visible, but collapse the
   topics under each heading unless that section is open (the section holding
   the current page starts open; click a heading to open or close it). */
.md-nav--primary > .md-nav__list > .md-nav__item--section > .md-nav {
  display: none;
}
.md-nav--primary > .md-nav__list > .md-nav__item--section > .md-toggle:checked ~ .md-nav {
  display: block;
}
.md-nav--primary > .md-nav__list > .md-nav__item--section > label.md-nav__link {
  cursor: pointer;
  pointer-events: auto;
}