[1BSP (One Big Stupid Problem)] - magnification of a div

[1BSP (One Big Stupid Problem)] - magnification of a div

Hi Guys, 
I've 1BSP, look my project  http://jsfiddle.net/luke984/RzmWp/ 
I have this site that has the squares, as you can see.
I would like to enlarge the square at click on one of them, but only for the central four.
The 5th located at the left, i want to use it like as a "button" to return all the square at the same size before the click.
I know, this is a stupid problem, but i'm going crazy
see ya 
tanx so much.
and sorry for my worst english.