I saw this question and I was able to convert HTML with a separate stylesheet to one with inline CSS. However, when I tried to run it in Google AppEngine, it complained
java.lang.NoClassDefFoundError: java.io.FileOutputStream is a restricted class. Please see the Google App Engine developer's guide for more details.
I worked around that problem then it complained again
Caused by: java.lang.NoClassDefFoundError: java.awt.Color is a restricted class. Please see the Google App Engine developer's guide for more details.
So I don't think I can use that CSSBox library. Is there another way to convert HTML to inline CSS HTML in Google AppEngine?