How can I find the CSS file and which line of the element?

[fanisme]

I wanna change the position of a element. But how can I find the related CSS file and which line is about the element? Thanks

[Design75]

I use Firefox with the firebug add on, it shows you what css is used for a particular element and in which file. Chrome has something similar, but I just prefer the one with FF

[schoolboy]

I use Firefox with the firebug add on, it shows you what css is used for a particular element and in which file. Chrome has something similar, but I just prefer the one with FF

Here's a screen grab of one of the sites I manage, using Chris Pederick's Webmaster Tools and Firebug