CSS style definition in DocBook XSL collides with external stylesheet

Dear all,

I have the following problem:

When writing an article and converting it to HTML, section titles have a 
somehow "built-in" style definition:

<h2 class="title" style="clear: both">

Unfortunately, this definition collides with the external CSS style 
sheet I have made for my personal purposes. Is there any way to 
deactivate this "built-in" style?

Cheers
Bernd