Sparkly offers you a possibility to adjust widgets' look&feel. Today you can easily modify colors. Font and widget's size are fixed and can not be modified on your own. However - we are working on such functionality and hopefully will be able to offer you customisable widget setup soon.
How to change widgets' colours?
First: go to Preview menu item, its located in top left corner of your screen
Here you can easily adjust colors of your widgets. There is a set of 3 pre defined colours Sparkly is using. Please remember to save settings when you change anything.