Font size in all browsers

Having problems with font sizes in some browsers? Here's the deal...

Resizing fonts is very useful when creating web pages, but sometimes the output is not as expected in all browsers, especially Internet Explorer. Why? Because IE doesn't agree resizing with pixels like other browsers: e.g.

div {font-size:25px;}
h4 {font-size:14px;}

they work perfectly in all browser but not in IE. Internet Explorer uses em units. So,
1em equals 16px