How to refer to a style that is in a GUI skin?

Question

JavaScript

I have several GUI styles (one in the example) that increase the size of the text in a button depending on the screen width.
var buttonstyle : GUIStyle;
buttonstyle.fontSize = Screen.width/12;
For convenience, I want to combine these GUI styles into one GUI skin (via Custom Styles). How would I need to change the code if for example "buttonstyle" is in "styles : GUISkin" ?