How to have a three column in node page I want to have a three column in node page, my page width is 940px, and one column is 300px + 20px right margin, so 3 column is 960px, but the main width is 940px, I want to 3 column in one row,  how to do that? how to modify node.tpl.php?
I don't understand why this isn't a simple case of changing your CSS? You're adding 20px to 940px so that equals 960px. You must either use CSS3 (box-sizing: border-box;) or minus your extra 20px from 940px...which would be 920px. Standard box model stuff but maybe I'm missing something in your requirements.