Sorry I's late because I have a examination tomorrow!ft~~~,just try this~!
<?php
if (isset($_GET['width']) AND isset($_GET['height'])) {
// output the geometry variables
echo "Screen width is: ". $_GET['width'] ."<br />\n";
echo "Screen height is: ". $_GET['height'] ."<br />\n";
} else {
// pass the geometry variables
// (preserve the original query string
// -- post variables will need to handled differently)