If you want to strip attributes from most? tags you can try using something like :
Code:
find:
<(/)?\b(h\d|[uod]l|[pisbuq]|hr|br|abbr|acronym|address|area|base|basefont|bdo|big|blockquote|body|caption|center|cite|code|col|colgroup|dd|del|dfn|dir|div|dt|em|font|frame|frameset|hr|ins|kbd|label|legend|li|map|menu|noframes|noscript|object|param|pre|samp|select|small|span|strike|strong|sub|sup|table|tbody|td|textarea|tfoot|th|thead|title|tr|tt|var)\b([^<>]+[^/])(/)?>
replace:
<\1\2\4>
You will however need to make _sure_ that you are not removing font formatting which might be important, for example: calibre often uses a span class to mark italic (etc) text, instead of <i> tags - read the CSS and replace the tags correctly. You will also need to regenerate if you leave in <h> tags. Remove tags as needed and well..., be careful.