Detect device, browser and version using javascript

The best way to decide which functionality to use is feature detection. If the feature exists then that  functionality is allowed to run. Libraries such as Modernizr give you feature detection out of the box or you can write your own.

Full page site with vertical centering using css only

One of the big trends on the internet is the full page site. It consists of a single page site with multiple sections which you can scroll through. The trick of this is to have each section fill the screen and to centre the content inside.