Reducing the automatic column width

We’ve tried reducing the width of table columns to both 0% and 0px, and neither of them have a satisfactory behaviour for checkbox fields.  Even with single character titles, there seems to be a minimum width beyond which we cannot reduce.

A friend reduced the margin CSS property on the input element which looked like it showed potential.  This seems a little fraught.

Is it possible to render those checkbox columns as tight as possible?

Thanks,
greg