html5 gui,html - Building HTML5 based GUI in python - Stack Overflow

This is the closest I found https://github.com/html5lib

If you're going to send it in HTML5, I see no reason to build a browser though, there are already many browsers, that have more people working on them, you'd be hard pressed to beat something like Firefox or Chrome, unless you have a specific feature you want, and then a plugin might be better. Generally building a custom browser like that is only useful if you either only want to do one very limited thing (like streaming a movie) or you want to use a different format (something like sending your version of HTML in an XML doc and parsing that and rendering it).

I also personally don't think Python is what you want to do this with, simply for a lack of compatibility with pretty much everything else at the current moment (not that you couldn't make things work, but it's not like you're going to download a Chrome plugin, change 3 lines of code and load it into your browser). I did see an example web browser in the wxPython docs, you could start there, I don't know what it does and what it doesn't do though unfortunately.