Set icon font as background in CSS property

[afrigal]

All I want to do is replace a background image in CSS with an icon font, not icon image.I can't get it done.This is the CSS property:\[code\].social-networks .twitter{background:url(../images/social/twitter.png);}\[/code\]This is the code in PHP:\[code\] <ul class="social-networks"> <?php if(my_option('twitter_link')): ?> <li><a href="http://stackoverflow.com/questions/13869618/<?php echo my_option('twitter_link'); ?>" class="twitter">twitter</a> </li> <?php endif; ?>\[/code\]The way I insert an incon font is \[code\]<span class="icon">A</span>\[/code\]