It's small enough to use in applets. The configuration of the UI Components is achieved using CSS which means it can share the same CSS setup as the web pages which display it. The following objectives are listed in order of priority:

1. Compactness: The library should strive to be tightly coded, at most a few hundred Kilobytes in .jar form.
2. CSS Support: Although it's not a full-fledged User Agent, it should adhere as well as possible to the latest CSS standard and make the best use possible of its parameters.
3. Simplicity: The interfaces should be simple and not overloaded. Classes should contain a minimal amount of extraneous functionality.
4. Speed: The responsiveness of the library's components should never feel laggy, or soft. The user should feel comfortable with the speed components are rendered and events are handled.
5. Resource-friendly: The library should use minimal memory and processor resources. Single-threadedness is preferred over using a thread for each component (ala javax.swing).