sclass HTMLBase is Htmlable {
  new LinkedHashSet<S> headStuff;
  new LS html;
  
  public S headStuff() { ret nemptyLines_flattenLists(headStuff); }
  public S html() { ret nemptyLines_flattenLists(html); }
  
  S complete() { ret nemptyLines_flattenLists(headStuff(), html()); }
  
  void css(S css) { headStuff.add(hcss(preprocessCSS(css))); }
  
  S preprocessCSS(S css) { ret css; }
}