Possible Duplicate:
Why em instead of px?
em
or
px
or
%
I always found px to be better, but why do people use em?
Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Please briefly explain why you feel this question should be reported.
Please briefly explain why you feel this answer should be reported.
Please briefly explain why you feel this user should be reported.
px is good, if you design for a single browser, screen dimensions, fonts, etc. This way you explicitly set the size of the elements of the page, and no exceptions are possible.
If your site is getting viewed in various platforms/browsers, where screen size varies, some fonts are unavailable, the user changes the browser font size, etc., then it becomes a good idea to use abstract measurements, such as em or %, because using them the system tries to automatically calculate sizes, thus making it harder for text to be truncated.