open header.html and find
function opendetailwindow() {
window.open('','detailwindow','toolbar=no,scrollbars=yes,resizable=no,width=640,height=480');
}
You can edit this code.
Try this one:
function opendetailwindow() {
window.open('','detailwindow','toolbar=yes,scrollbars=yes,resizable=yes,width=800,height=600');
}