body {
  margin: 0;
  padding: 0;
  background: var(--surface);
}

main {
  width: 65rem;
  margin-left: 240px;
}

aside {
  width: 200px;
  position: fixed;
  top: 0;
  bottom: 0;
  padding: 8px;
  display: flex;
  align-items: stretch;
}

aside .treeview {
  width: 100%;
  /* TODO: Move scrollbar into the recessed region? */
  overflow-y: scroll;
}

h1 {
  font-size: 5rem;
  margin: 12px 0;
}

hr {
  margin: 0;
  border: none;
  width: 400px;
  height: 1px;
  opacity: 0.5;
  background: linear-gradient(
    to right,
    red 20%,
    yellow 20%,
    yellow 36%,
    green 36%,
    green 60%,
    blue 60%,
    blue 100%
  );
}

h2 {
  font-size: 2.5rem;
  margin-bottom: 12px;
}

h3 {
  font-size: 2rem;
  margin-top: 20px;
  width: 120px;
}

p {
  max-width: 50rem;
  line-height: 1.5;
}

.component {
  display: flex;
}

.component > div {
  margin: 12px 0 0 32px;
  padding-left: 32px;
  border-left: 1px solid var(--button-shadow);
}

blockquote {
  margin: 0 0 20px;
  padding: 20px;
  background: var(--button-face);
}

blockquote footer {
  margin: 12px 0 0 12px;
}

.example {
  margin: 12px 12px 24px;
}

details {
  margin: 12px 0;
}

button.focused {
  outline: 1px dotted #000000;
  outline-offset: -4px;
}

button.active {
  box-shadow: var(--border-sunken-outer), var(--border-sunken-inner);
}