CSS Support in Browsers
CSS support varies for different web browsers. Internet Explorer is the best example of an internet browser that does not support all the features of CSS. Internet Explorer 9 (IE9) does a better job than its predecessors at supporting CSS. There will be cross-browser CSS issues for years to come (if not always). This has to do with browsers being separate products from different companies and by nature will never be exactly the same. It will always be important to test your webpages across all the popular browsers (Internet Explorer, Firefox, Chrome, and Safari).