As Greg says, things like colors, fonts, spacing/padding, borders, backgrounds,and more are set by creating a style (like a CSS style in HTML).
Add a new Web Style to your app
Add the Properties that you want to affect
Apply that style to your control in the control’s property inspector
I wish that we had something like this for Desktop apps. There we have to create new subclassed controls and the settings we apply to one control can’t be easily applied to other, different types of controls (i.e.: PushButton to Label).