JQuery - 1em to pixels
function em2pxl(){
// how many pixels in 1em
var div = $('<div style="width: 1em;"></div>').appendTo('body');
var em = div.width();
div.remove();
// console.log('1em = ' + em + 'pixels.');
return em;
}
// source: http://forum.jquery.com/topic/how-do-tell-how-many-px-are-in-1em