The standard button can be customized with styles, e.g. Slider button or Text button. But there are more additional styles for a button.
Our button has a minimum size of 48×48 pixels. This is necessary for touch events because your fingers need some space for device contact. But sometimes 48×48 is too much. To style a button on your own, just use:
Style.addStyleNames(button, "f_small");
and the button size is as it is.