If you use firefox you can get many great
addons for web development. Firebug will allow you to trouble shoot javascript and has a tab for editing css on the fly to see its effects. This can be useful to see how others do their designs.
If you are just trying to find out if they are using it unless they are in 1994 they probably are in some way. Check the link htmlbasictutor posted and it should show you where to look to see if they are using it.