I need an explanation of this

I am not new to CSS but today I saw something I didnt know could be done. I saw this when viewing the code at www.stuffandnonsense.co.uk.

body[id="stuffandnonsense-co-uk"] { 
padding : .5em; 
font : 70%/160% Tahoma, Verdana, "Lucida Sans Unicode"; 
background : #fff; 
color : #000; 
text-align : center; }

What I was ignorant of is the fact that you can put selectors inside of brackets.


Can anyone explain this to me? I have been browsing the internet for an answer but I have yet to find one. Also I have not read it in any books. Is this some kind of css3 ability or what?

One other question I might add. What is the deal with the font property having the 70%/160% is that actually giving font sizes? Didnt know you could do that either.