Stylesheet in replied-to embedded HTML message overrides MailMate theme

When I reply to an HTML message (and it gets embedded), and that HTML contains a <style> tag, the contents of that tag seem to override the CSS defined by my chosen MailMate theme.

For example, messages that I receive from Outlook users often contain:

<style type="text/css" style="display:none">
/*<![CDATA[*/
<!--
p
        {margin-top:0;
        margin-bottom:0}
-->
/*]]>*/
</style>

and this causes my reply to lose inter-paragraph spacing as well.

I have tried both Inline CSS (with Premailer) and Scoped Stylesheet.