I'm not sure what people like about Personas (or the equivalent in other browsers). It always stands out, distracts, and for me even messes up the great website

I'm not sure what people like about Personas (or the equivalent in other browsers). It always stands out, distracts, and for me even messes up the great website I may be viewing at the time. I'd be much more interested in a CSS extension that lets websites 'bleed' their background into the browser chrome.