CSS - CSS Compatibility
Since most web browsers are periodically updated, compatibility is no longer a problem. Although you may need to run your web page via validator or test the page with the browser you are worried about. As soon as you do this, you will be able to find things that should be edited.
Another essential way is to search for compatibility charts or lists which show you the behavior of a certain browser dealing with compatibility for CSS properties. Nevertheless, if you want to test the way your web page will look like in some specific browser, you need to:
start the new Internet Explorer session
click Internet Options tab in Tools menu
click Accessibility tab in the opened dialog box
check all positions in Formatting section, make sure you have checked Font Styles
Double click OK.
After the dialog box is closed you are able to see the way your web page is displayed in the browser which does not support CSS formatting. There is plenty of solutions which may help, but unfortunately, not a single one that will improve all the formatting styles at once.