When comes to the issue of change the style of OpenERP, sometimes I have to write css to overwrite all specify rules for one particular selector in order to make it work. For example, if I want to change the background-color of .oe_topbar class, change only background-color property doesn't work, I need to crawling to find background-image property and turn it off. Something like this.

As the title said: Do you have an effective way or any tips to overwrite css ?