how to change transparency of GUI.Button via GUI.skin?

I'm using my own custom GUISkin, but I'm not sure how to change the transparency of a button. For instance, no matter what I change the texture to (in the normal state), it is always mostly transparent. But I need a solid button with no transparency.

Hi,

the transparency is controlled via a backgroundtexture, in your GuiSkin>> Button>>Background. You can change this texture or you load http://unity3d.com/support/resources/assets/built-in-gui-skin , where you find all buttons and .psd with the source.