Adjust width of a single column in a grid.

I have a series of grid questions that have 5 columns total (column based direction). The first 4 are dropdowns and the last one is numeric. I have the width of labels column set to 50% but I want the 5th column to be wider than the first 4. I have tried the script below and it does seem to work if I apply it to columns 1-4 but when I apply it to the 5th column it seems to have no effect. I've played with the percentage but still no change to that last column.

I'm hacking it by making the numeric input wider, but I'd prefer to have the column itself wider, not the input box (due to the text at the top of the column).

Here are the two scripts I've tried that do work on the other columns.

<style type="text/css">
.grid_c5
{width: 50%;}
</style>

<style>
#[% QuestionName() %]_div .inner_table > tbody > tr > td:nth-child(6) {
width: 50%;
}
</style>