At TravelTripper, we make hotel reservation software. Our main product is a "booking engine" called RezTrip, a web based application that allows visitors of a hotel’s website to directly book a stay with that hotel.
As GWT applications go, we think RezTrip, when it comes to the question of styling, presents an interesting departure from traditional development. As a "white label" application, we needed to create our app in such a way that allows our hotel clients the ability to customize not only the "frame" around the application, but also the internal style of the application itself, such as fonts, colors, etc.
In other words, each hotel needs the ability to create their own custom header, footer, or sidebar and have it wrap the booking "application" portion of the page. Furthermore, each hotel needs to be able to change all the colors, fonts, and even some icons within the application.
The desired end result is a single booking engine application, running on multiple web sites, but always mimicking the look and feel of each individual hotel site.
Read the whole article at: Styling and Skinning Your Apps With GWT