Font selection is an important part of web design and development. The designer does not only need to pick a beautiful font that matches the design style, but also wants this font in the real website to be rendered as close as possible to her design. We have four choices for font size unit when it comes to CSS font-size – pt (point), px (pixel), em and percent. Knowing when to use the proper unit is essential for your web page rendering. If you are not careful enough about the font size unit, you web pages may end up great in some browsers, ugly in some others, and broken in rest of browsers.