Stylebox

An extension for developers to inject custom cascading style sheets (CSS) into a web page.

Stylebox allows you to quickly demonstrate different user interface and user experience designs of a web page.

For example, follow these steps to see how the extension works:
1. Install the chrome extension
2. Go to: http://bit.ly/QGOFhX
3. Click the "Stylebox" extension
4. Use this stylesheet: http://bit.ly/Uw5n7o

Source code available at :
https://github.com/awoo/stylebox


Also, a website design that successfully demonstrates a compatible & suitable design for all mobile devices:
www.interestingbydefault.com