Adobe Muse uses WebKit as its rendering engine for Previews. WebKit is an open source layout engine, which was created to allow web browsers to render web pages. It powers the Apple Safari and Google Chrome browsers. It is also used as the basis for the experimental browser included with the Amazon Kindle eBook reader, as well as the default browser in the iOS, Android, BlackBerry Tablet OS, and webOS mobile operating systems.
This means that when you preview your page or your site from within Muse, you'll get a pretty good idea of how it will look on all the browsers mentioned previously.