jQuery UI accordion widget: How to change CSS

jQuery UI accordion widget: How to change CSS

Hello,
i try to use the accordion widget with the default example (see http://jqueryui.com/accordion/).

my code snippet:
<div id="accordion">
           <h4>Einstärkengläser</h4>
           <div>Einstärkengläser braucht man, ........ </div>
           <h4>Bifokalgläser </h4>
           <div>Bifokalgläser bestehen aus 2 Teilen, .... </div>
           <h4>Gleitsichtgläser</h4>
           <div>Komfortabel sehen ...
....                      

 </div>


The <h4> in my CSS-file is blue colored and bold,
but it looks like the default example and I cannot find another CSS-File where I could change the attributes.

Any ideas?

Thanks for help