Hi Achilleas,
you can use this article with help to debug and fix CSS issues:
http://kanev.com/blog/19-joomla-components-css-override
If this doesn't help you may wish to call for support your template provider as this is template issue, not Taxi Booking.
If they refuse to provide you with support please let us know and we will try to help you although template issues are not in the scope of Taxi Booking support.
If you still have troubles please provide Temporary back end and FTP log in details to your website in a PRIVATE ticket so we can take a closer look and help you with your issue.
Issue description:
Ftp server:
Ftp user:
Ftp password:
Website URL:
Back end URL:
Super user:
Password: