If you are wanting to build a webapp I can't recommend yeoman enough.

It allows you to scaffold out your project really quickly, easily and following best practises.

If you are familiar with Rails you will know how powerful that can be not having to worry about configuring boilerplate stuff.

You get loads for free: + Separate tasks for watching files with live reload developing and compressed build version + Compressing your images and minification + SASS plus bootstrap if you fancy + Tests + etc

Looks nice and really clean.

Just FYI the light source on the iphone desk image is obscuring the text "Preview" on iOS.