[Zope] not authorised to access this resource

sorry if this is a simple question... i have some restricted folders in a zope site and i'm using acl_users and roles to control access. when the username and password box comes up and someone hits cancel, zope(?) generates the following line of text: you are not authorised to access this resource. username and password are not correct. my problem is the code it generates: <strong>you are not authorised to access this resource.</strong><p> username and password are not correct. the text is fine, but when it goes into my dtml page it is playing havoc with my layout and css. where can i find this error message so i can amend the html tags? cheers matt