* { box-sizing: border-box; }

body {
  margin: 2em;
  background-color: #fff;
  font-family: serif;
  font-size: 16px;
  line-height: 20px;
}
  .is-expanded #expand { display: none; }
  .is-expanded #collapse { display: block; }

.l-document { width: 85%; }

ol {
  margin: 0;
  padding: 0;
}
  .child {
    display: none;
    padding: 0 1em;
  }

ol > li {
  vertical-align: top;
  width: 100%;
  list-style: none;
  transition: background-color 0.25s;
}
  ol > li:before {
    content: attr(data-name);
    margin-right: 0.5em;
    font-family: sans-serif;
    font-size: 14px;
    font-weight: bold;
  }

li:hover { background-color: rgba(0,0,0,0.1); }
  li:hover > .content { text-decoration: underline; }

.content { transition: color 0.25s; }

.is-parent { cursor: s-resize; }
  .is-parent:hover > .content { color: #00f; }
  .is-parent.is-open { cursor: n-resize; }
    .is-parent.is-open:hover > .content { color: #f00; }

.is-childless { cursor: default; }

.is-highlighted {
  background-color: #ff0;
}

.l-menu {
  position: fixed;
  top: 0;
  right: 0;
  padding: 1em;
}
  .menu > a {
    display: block;
    cursor: pointer;
    color: #000;
    line-height: 1;
    font-family: sans-serif;
    font-size: 14px;
    font-weight: bold;
  }
    .menu > a:hover { text-decoration: underline; }

#expand:hover { color: #00f; }

#collapse { display: none; }
  #collapse:hover { color: #f00; }

.separator {
  margin: 0 0.25em;
  opacity: 0.25;
}