Thus, when you ask a question in this community, please tell us what browser you are using and what version of it. Also bear this in mind if you are following a solution given and the CSS just doesn't do what it's supposed to. If you are posting an answer to someone's query, please say which browsers you know it does work on, if you can, e.g. "This solution is known to work with Firefox v.1.0.6"
This page gives a good list of which elements are compatible which which browsers and to what extent. Well worth a look if something is not doing what you expect.
In terms of which browser we would recommend, Firefox is very reliable for parsing CSS correctly - you can download the latest version here (it's free). I'm not going to promote it's many virtues here (and there are many), but suffice it to say it is far more CSS standard compliant than Internet Explorer and layouts will generally look and work much better on it.
CSS Browser Compatibilities