How to change the color of control buttons

Some of the control buttons are rendered with a bright green background for example the submit boxes on checkout page for "register and checkout" and "checkout as guest". I would like to change the color of those control buttons. Can you please advise how I could accomplish that. It does not appear to be configurable in template color parameters. Can you please advise where to find the css code that determines the "green" color for the control buttons? . The green buttons are not just on my web site they are also visible in your on-line demo of this template.

THANKS for your help on solving this. Best Regards

found a png file in components\com_virtuemart\assets\images\vmgeneral\

that seems to be the source of the "green" color buttons. swapped that graphic out and now have better colors on this

Is this the best way to do this .. is thera any way to configure this via the template parameters ?

Way you did it is ok way