Since I've posted this , I had an open message with SAP regarding this issue.
according to SAP , the reason for this problem lies within our use of a non-standard Corbu CSS File .
Just to make things clear: The only change I did in the standard CSS file was the pointing to our Company LOGO (instead of the original 'clouds.jpg).
I've just followed the standard procedures (instead of using the original SAP BSP application THTMLB_STYLES , I used the new Skin workbench to copy the original skin Corbu to our copied BSP Application ZTHTMLB_STYLES7 . I used the new 'define CSS path' in a standard way . We will have to go live like that as we can't make any changes a week before go live , but I still think that it's an SAP standard issue . You don't suggest we would add the url to our Logo Image in the original SAP BSP application and change the standard thtmlb_stand.css ?
Please see the attached css files (as txt) .
Thanks, Kai