The initial version of the Element 4.03 wasn't done properly as it was supposed to be done using the stylevars. It was all manual hard coded in the css and hence there were so many issues and bugs with the style. Beginning with 4.06 the styles were re-done using Stylevars.
You may still be able to put those modifications in the 'additional.css' template and it could work, but I can't guarantee that.
Regards,
Ketan