Because my custom css is part of my theme (Thesis), it loads before the plugin css. I see that, in the latest plugin version, you have added the !important tag to the button text color. This means that I can't change the text color using custom css because it is overridden by the plugin css.
I'm not too sure why you have used the !important tag, because, when I remove it, everything works fine.
Could you remove it from future updates so that I don't have to edit the plugin css, please?