How to get screen resolution of visitor in javascript and/or php?

javascript, jquery, php

Solution

What makes you think people always have their browser window maximised to the same size as their screen? I don't, and I'm not the only one.

What you want is to cover 75% of their window. This can be done using CSS; if the element in question is a child of the body element, then

#box {
    position: absolute;
    top: 12.5%;
    left: 12.5%;
    width: 75%;
    height: 75%;
}

will probably do it (I've not tested it, though).

EDIT: I've now tested it, adding

html, body {
    width: 100%;
    height: 100%;
}

and it worked as expected, at least in Firefox 3.5 :-)

Problem

I would like to know the screen resolution of a visitor visiting my page so I can properly make a jquery thickbox cover about 75% of their screen. Solutions to the question or helping me solve my problem are greatly appreciated!

Original source