I am having alignment issues with my output panels. They render fine when the page loads, however after a re-render they are not aligned.  See image and code below.

 <apex:outputPanel id="searchResults" style="width:600px;float:left;"> 
   <apex:pageBlockSection columns="1" title="Service Tasks" id="SearchResultsection" > 
		
		<apex:pageBlockSectionItem >
		<apex:commandButton value="Add Service Tasks" action="{!processSelectedST}" styleClass="btn"/>
		<apex:commandButton value="Clear Selection" action="{!refreshSTList}" styleClass="btn"/>
		</apex:pageBlockSectionItem>
		
   <apex:pageBlockTable value="{!ServiceTaskList}" var="STitem" id="STtable">
                            <apex:column headervalue="Select">
                              <apex:inputCheckbox value="{!STitem.selected}"/>
                          </apex:column> 
                              <apex:column headerValue="{!selectedServiceCategory.Name}" value="{!STitem.ST.Name}" /> 
                       </apex:pageBlockTable>    

   </apex:pageBlockSection> 
  </apex:outputPanel> 
  
   <apex:outputPanel id="relatedcategoriespanel" style="width:400px;float:left;"> 
   <apex:pageBlockSection columns="1" title="Related Categories" id="relatedcategoriessection" > 
   
     <apex:dataList value="{!RelatedServiceCategories}" var="RSC" id="relatedservicecategorieslist" type="None">
                   
                 <apex:commandLink value="{!RSC.Related_Service_Category__r.Name}" action="{!refreshSTList}" reRender="STtable, relatedcategoriessection, ServiceCategoryList" >
                    <apex:param name="relatedSCparam" value="{!RSC.Related_Service_Category__c}" assignTo="{!selectedServiceCategoryID}"/>
                 </apex:commandlink> 

        </apex:dataList>
   
    </apex:pageBlockSection> 
  </apex:outputPanel> 

Thanks,

RN