GWT - Problems styling a TabLayoutPanel

I want to implement a horizontal navbar using a TabLayoutPanel, using custom styling to fit my needs.

But I don't know how to override the default styling. Here's the UiBinder template:

<!DOCTYPE ui:UiBinder SYSTEM "http://dl.google.com/gwt/DTD/xhtml.ent">
<ui:UiBinder xmlns:ui="urn:ui:com.google.gwt.uibinder"
  xmlns:g="urn:import:com.google.gwt.user.client.ui">
  <ui:style>
    .gwt-TabLayoutPanel .gwt-TabLayoutPanelHeader {
      background-color: red;
      padding: 0;
      margin: 0;
    }
  </ui:style>
  <g:TabLayoutPanel barHeight="3.75" barUnit="EM">
    <g:tab>
      <g:header>Latest</g:header>
      <g:Label>Latest Activities</g:Label>
    </g:tab>
    <g:tab>
      <g:header>Patients</g:header>
      <g:Label>Patients</g:Label>
    </g:tab>
  </g:TabLayoutPanel>
</ui:UiBinder>

This doesn't work. But how can I reference the default styles?

attach a separate css i think - inline styles are for use with {style.xyz} in the same template. Actually there's a second solution. If you insist on having it in the ui.xml - use external scope: http://code.google.com/webtoolkit/doc/latest/DevGuideClientBundle.html#External_and_legacy_scopes