Hello, everyone again

Keep playing with VF. Came across this: (if this is a VF page) I insert in a page layout 

<apex:page standardController="Account" showHeader="true" tabStyle="account" >
   <style>
      .activeTab {background-color: #236FBD; color:white; 
         background-image:none}
      .inactiveTab { background-color: lightgrey; color:black; 
         background-image:none}
   </style>
   <apex:tabPanel switchType="client" selectedTab="tabdetails" id="AccountTabPanel" tabClass='activeTab' inactiveTabClass='inactiveTab'>   
      <apex:tab label="Details" name="AccDetails" id="tabdetails">
         <apex:detail relatedList="false" title="true"/>
      </apex:tab>
      <apex:tab label="Contacts" name="Contacts" id="tabContact">
         <apex:relatedList subject="{!account}" list="contacts" />
      </apex:tab>
      <apex:tab label="Opportunities" name="Opportunities" id="tabOpp">
         <apex:relatedList subject="{!account}" list="opportunities" />
      </apex:tab>
      <apex:tab label="Open Activities" name="OpenActivities" id="tabOpenAct">
         <apex:relatedList subject="{!account}" list="OpenActivities" />
      </apex:tab>
      <apex:tab label="Notes and Attachments" name="NotesAndAttachments" id="tabNoteAtt">
         <apex:relatedList subject="{!account}" list="NotesAndAttachments" />
      </apex:tab>
   </apex:tabPanel>
</apex:page>

 I get multiple views displayed one after the other of the same content.

WHat am I missing?

Appreciate your help, 

PG