indicates that this HTML uses the standard Hudson layout.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@33160 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/resources/lib/layout/layout.jelly

@@ -53,6 +53,7 @@ THE SOFTWARE.
     </st:attribute>
   </st:documentation>
 <st:header name="Expires" value="0" />
+<st:header name="X-Hudson-Theme" value="default" />
 <st:contentType value="text/html;charset=UTF-8" />
 <!-- The path starts with a "/" character but does not end with a "/" character. -->
 <j:set var="rootURL" value="${request.contextPath}" />