In JavaFx, we can apply CSS style to the nodes. For example, if we want to define a style for the buttons, the style sheet will have the selector named as ‘.button’. The same way, TextField defines a UI class in JavaFx, and the selector will be named as ‘.text-field’. Note, as text field control is a two-word class, in the selector we will have a hyphen. When defining the rules, we must prefix each rule with ‘-fx-‘. In this example, we will define style rule for a JavaFx Button.