// Ensure any lists only contain `li`s as children.
ul > *:not(li),
ol > *:not(li) {
  @include error("<ul> and <ol> should only contain <li> as children");
}

// Definition lists should only contain DT and DD elements
dl > *:not(dt):not(dd) {
  @include error("<dl> should only contain <dt> and <dl> as children");
}