Good article, I’ve been using the same method but with the quick & dirty bit of js below for the last year or so and find it much quicker to code and maintain this way compared to using myriad css hacks

if (navigator.vendor != null) {
if (navigator.vendor.match(/\bApple\b/)) {
document.write(’<link rel=“stylesheet” type=“text/css” media=“all” href=“styleSafari.css” />’);}}
if (window.opera && window.getSelection) {
document.write(’<link rel=“stylesheet” type=“text/css” media=“all” href=“styleOpera.css” />’);}