If you set the fieldset border to 0, it's impossible to get do be showing correct again by setting it to "1px solid #ccc".
This is a bug in the fieldset element.
If you do tuch fieldset border, the top left corner of the fieldset are be different from not tuching it. (missing some part off the top border that shuld come before the legend.)
It will never be the same after you have starting tuching the border px.
You can change color on it then.
But my point is that if you want ot have nice filedset borders, the gantry.css can't set it to 0 in line 9 there.