Made by legendary Sofa specifically for Cappuccino, since Aristo's launch in 2009 with Cappuccino 0.7 it has been ported to multiple other UI toolkits, a testament to its versatile strength.
Two versions of Aristo exist and are included in Cappuccino 0.9.7 and above:
Aristo 1 is meant to provide a solid "app" feeling in the browser, and to look good in any browser, whether it’s Firefox, Safari, or even Internet Explorer, Mac and Windows. It's the classic Cappuccino look.
Aristo 2 is the successor which provides a lighter more "web-like" look. Built on the desire to "under promise and over deliver", Aristo 2 has a more humble appearance which can serve to make the advanced features of Cappuccino a pleasant surprise while at the same time not carrying over desktop expecations that may not translate well to the browser.