CSSBox is an (X)HTML/CSS renderingengine written in pure Java. Its primary purpose is to provide a complete information about the rendered page suitable for further processing. However, it also allows displaying the rendered document.
SwingBox is a Java Swing component that allows displaying the (X)HTML documents including the CSS support. It is designed as a JEditorPane replacement with considerably better rendering results. SwingBox is pure Java and it is using the CSSBox renderingengine for rendering the documents.