XHTML 1.0 Strict

Hi
I'm running my website with the XHTML 1.0 Strict DTD
Can I modify the output of some widgets to suit my Doctype
For exemple :
Strike <span style="text-decoration:line-trought"></span>
U <span style="text-decoration:underline"></span>
Etc.

and some attributes like :
<p dir="rtl"> <p style="direction:rtl">
Thank's