Browsers are in the business of keeping up with the current trends in the market i.e smart phones and tablets, so your new site will not look or function the same on all browsers.  We utilize the Google’s support standards for browsers; current and prior major release of Chrome, Firefox, Internet Explorer and Safari on a rolling basis. Each time a new version is released, we’ll begin supporting the update and stop supporting the third-oldest version.”http://googledocs.blogspot.com/2011/06/our-plans-to-support-modern-browsers.html