I've added a VF page component to the top of a page layout using the "issue" severity format.  Works fine but there is an annoying white line that appears at the top of the page section.  What do I need to to remove this/set it to the background colour?

The VF page is as follows:

<apex:page standardController="xxx__c" tabStyle="Terms_of_Business__c">

<div id="training_message" style="height:80px; background:#F3F3EC;" >

<apex:pageMessage severity="info">

    Click <apex:outputLink target="_blank" value="xxx" id="record1">here</font></apex:outputLink> for a demonstration of adding a Terms of Business record<br>

    Click <apex:outputLink target="_blank" value="xxx" id="record2">here</font></apex:outputLink> for a demonstration of submitting and approving a Terms of Business record<br>

    Click <apex:outputLink target="_blank" value="xxx" id="record3">here</font></apex:outputLink> for a demonstration of sending emails for a Terms of Business record</apex:pagemessage>

</div>

</apex:page>

The page section is set to 80px.

The white line looks like:

Any suggestions would be much appreciated.