when using custom background gradient, also set background-color

as a fallback in IE9.

Because the font-color is set, when using custom colors, the buttons might end up not readable, because IE9 does not support background-gradient.

So I simply added background-color and set it to the one specified in the options as background.



TODO: Right now the background-color is set within the loop, so it is actually set 4 times. I left it like this for brevity/readability. You might want to change it.

TODO: Update minified version.