I see. Thank you for reporting this. There are a few pieces in place so these errors are very difficult to track and fix:
- Evernote uses its own HTML subset of supported tags
- We use an WYSIWYG editor to render notes and edit them, which also has some HTML particularities (Ckeditor)
Due to this we won't give fixing this a high priority, unless we can find a case that is specific and affects many users (we had such case with gmail notes some time ago).