If you develop using firefox then its something that you should definately use
http://getfirebug.com/It allows you to inspect code in a site and debug it.
IE has a developer plugin as well... although its an inferior attempt at copying firebug... I'm unsure about some of the other browsers.
Do you have a link to your dev site? or are you able to provide the working files? It's a bit hard to think about what might be the issue without seeing anything.
