Flex：按钮样式弄乱了FlexChrome

My air app is using the FlexChrome instead of the system chrome. The problem is I also have a .CSS for skinning that sets the skins for the Button class. This is also changing the 3 buttons (minimize, maximize, close) in the flex chrome which is undesired. Is there a way to make it not effect the Flex chrome buttons?My air app is using the FlexChrome instead of t