Sizing text for the screen using ems in your Cascading Style Sheet (CSS) can be a problem, if you are not a web designer and have never spent any time reading about the differences between the various units that can be used to measure text size, especially pixels (px) and ems (em) which are the most frequently used. I am sure there are a lot of guides out there that explain the issues that arise by using either one of the aforementioned units, but I consider the article How to size text using ems a very good place to start, if ems is what you aim for.
It seems that the main advantage of using ems instead of pixels is that text size can be translated correctly by all major browsers when the user resizes the text from within the browser, overriding the text size defined in the CSS. I feel that, once again, people are forced to waste their valuable time because of Microsoft’s old-fashioned methods of protecting its investment by not following the established standards, so… well, taking into account that Internet Explorer (IE) is still a very popular web browser, I guess that noone can actually avoid reading about the pros and cons of using ems or pixels to size text for the web.
The Size text with em in your CSS – Explained with example by George Notaras, unless otherwise expressly stated, is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License.