Opps was way off on what you sought - thanks for the url as this directed me to what you are seeking. You can try adding these entries to your stylesheet.css file and only insure that they total 100% as this is all the space you have and I would use percent over px or em to keep this fluid for other resolutions.
Code:
#listCell0-0 {
width: 10%;
}
#listCell0-1 {
width: 50%;
}
#listCell0-2 {
width: 20%;
}
#listCell0-3 {
width: 20%;
}
You will also have to check other listings as this uses the same tabular layout as other items and the same tags. If this messes up others post back and we will have to get a bit more crafty with the definition