If you are seeking tutorials, or UI libraries etc, sorry, I can't help you with that as I am unaware of those things. However, if you are asking from which aspect to start building one from scratch, I would say start with layouting. Try implementing a tiny subset of div related things like position and display and see if this is what you want to spend your time working on. Even if you can crack this thing easily, remember, this is just the tip of the iceberg. I am not discouraging you, but know that you would have to digest the entire DOM and HTML spec, not to mention have a JavaScript engine and implement all the security related intricacies, at the least, for your software to become a web browser.