.rmenu {
  flex: 0 0 180px;
  min-width: 180px;
  overflow-y: auto;
  position: sticky;
  top: 0;
  align-self: flex-start;
  max-height: 100%;
}
#rnav a {
  display: block;
  padding: 6px 10px;
  text-decoration: none;
  color: black;
  border-radius: 3px;
}

#rnav a:hover {
  background: lightgrey;
}

#rnav .selected {
  color: white;
  background: #595959;
}

#rnav .heading {
  padding: 8px 10px 4px;
  font-weight: bold;
  color: #444;
  border-bottom: 1px solid #ccc;
  margin-bottom: 4px;
}