In case I ever need it again, this is the CSS to force a "proper" ordered list hierarchy all the way to 6 layers deep. (pro tip – if it's 6 layers deep, you're doing something wrong)

<style type="text/css">
  OL { list-style-type:upper-roman }
  OL OL { list-style-type:upper-alpha }
  OL OL OL { list-style-type:decimal }
  OL OL OL OL { list-style-type:lower-roman }
  OL OL OL OL OL { list-style-type:lower-alpha }
  OL OL OL OL OL OL { list-style-type:lower-greek }
</style>