Please don't use !important ever.  If there really is some legacy code that uses it that you have to override, either try to clean up that code or add a comment with a reason for using !important.  In this case, I did a quick test and removed !important and it still worked fine, so maybe you can just remove it. 

Also, just FYI, the current (soon to be old) grid system uses an "alpha" class to denote the first column in a grid, so that is available to you as well (and would work in IE8 which is optional as we no longer support that browser).