Need help with idea of java css web browser

Hello everyone.
I have big problem. I need create desktop aplication in whitch can show web pages. This is my vision.
http://skorpikon.kavepecko.eu/images...0aplikacie.jpg
In block 3 will be CSS code. If I change something in this block that show me change on page in block 1. In block 1 will be something like web browser.
If i click on icon IE show page like Internet Explorer, if i click of ico FF show me page like Firefox,...
I want create somethink like that YouTube - Skybound Stylizer (CSS Editor) Introductory Video but not so complicated

I dont have idea how can i do it. PLS help me. What i can use for doing block 1?
PLS write me something ideas for creating this application.
Thanks for help :)

Are you experienced with java? This will take a pretty strong understanding of many different topics. What type of stuff do you know?

I am not a beginner but not very advanced. I am a student in college. I had 4 semesters of programming in Java. A year ago I made ​​a program to generate a solution wordsearch.

Get html code from sites I know. Process css code as well. I do not know how to display the site in the first block Everything would be going to local data. First, I would have pulled the entire page and then edit it. It would not be a problem.

What else should I understand? What topics would you recommend me to look at and to study?