Adjust font size of a related list on Visualforce page rendered as PDF

Hi,

I've included an apex:related list for approval history into a Visualforce page being rendered as a PDF however its coming out in a font that is much larger than the font used elsewhere in the visualforce page.

Is there a way to adjust the font size of the apex:related list data or do I have to rebuild as a controller extension??

<apex:page standardcontroller="Opportunity" showheader="false" contenttype="application/pdf" renderas="pdf" readonly="true" >
     

<apex:relatedList list="ProcessSteps" >
</apex:relatedList>

Thanks in advance