https://stackoverflow.com/questions/4912092/using-html5-canv...
Suggested tool by best answer was this. https://github.com/niklasvh/html2canvas
It using html2canvas[0] to rasterize the browser rendering into a canvas, upload it to WebGL, apply effects and patch-back events(i.e. mouse clicks) back to the hidden browser dom elements. (On the other side, font hinting and such are not really a problem)
Implementing full UI framework over WebGL has it merits, and hopefully someone will make a useful(and not html+css based) one some day.
The only thing I could come up with was using something like HTML2Canvas[1] to render a portion of the DOM in a canvas/image, position that exactly on top, and then blur that. But all that seems quite convoluted and heavy, so decided not to invest any energy into it.
But.. I'm not sure it's going to work out too well. You'd probably do better off using a service like http://webthumb.bluga.net/home but it gets complicated quickly (although it's been a cpl years since I looked into this so things may have come along).