The website has under gone a few changes recently making it much more useable on mobile and tablet devices. Any screen sizes less than 960 pixels wide should pick up the changes, as long as they support CSS media queries. This should be all the latest browsers on phones and tablets, as well as all the latest desktop browsers.
Here is a screenshot of how one particular page displays on a mobile device.
There have been a fair few changes made to the stylesheets, and the jQuery javascript version has also been updated. Therefore, if something is not appearing right or not working, chances are your browser is loading cached versions of the stylesheets or javascript files. Either clear your browser cache, or a force refresh of the page should be sufficient.