Button background color using CSS

Hi,

I'm trying to change the background color of a button when it is enabled.  I've created a custom file "test.css" and set it in the Custom CSS property of the application.

My script as follows:

BUTTON_1.setEnabled(true);

BUTTON_1.setCSSClass("buttonenabled");

test.css:

.buttonenabled

{

  background-color:green;

  background:green;

  color:black;

}

The text color is changed to black but the button background is still silver (default color).  Does anyone know whether there is a way to overwrite the default background color?

Thanks,

Jianyun