An alternative (or addition) to submitting html files, could be to submit txt2tags source code ( http://txt2tags.org ). It is plain text, compiles to html and mediawiki and is easier than html.
The usage of html is a relic from the process of copying of the submission rules (in large parts) from the Oberwolfach Collection that should have disappeared long ago anyway. The submission should imho be wikitext since that is what we want. - J. Saak