The appearance of UI-Controls in Java FX can be either configured programmatically, or with CSS. See this comprehensive CSS reference. Hopefully it will be distributed with the official SDK doc in the next release...
Its a kind of "Convention Over Configuration" again :-).
Java EE 7 Workshops: Bootstrap, Effective, Architectures, June, 13th-15th, Munich's Airport
On demand workshops: Java EE 7 Bootstrap, Effective Java EE 7, Java EE 7 Testing and NEW: Java EE 7 Microservices are available for streaming