You can change the size of any face by providing a size facet. The size can be an integer or a pair. An integer specifies the width of the face. A pair specifies both width and height. Images will be stretched to fit the size.
Most styles have a default color.
For example the body of buttons will default to a teal color. Each component can range from 0 to 255. The effect of the color depends on the style. Most faces will accept text to be displayed. Even graphical faces can display text.