Tag cloud widget

I’m using the default tag cloud widget that comes with WordPress to do a tag cloud and I’m wondering if there’s a way I can apply color styling to the different sizes? I see that it puts the font size in-line based on the occurrences of the tag but there doesn’t seem to be a way I can change the color (via CSS or another way). For example I want the larger tags to be a darker color and the smaller ones to be lighter color. How can I do this?