Change grid CSS

In one particular grid in our application, I need to adjust the white space and padding CSS to something like:

white space: pre;

padding: 0px 10px 0px 10px;

As opposed to these values defined by .x-grid-cell-inner.

I've created a new class and applied it to the itemCls parameter of the grid view, however in this class things like font size change OK but 'white space' seems to still be overridden by .x-grid-cell-inner, even if I specify !important.

Any suggestions?

Change grid CSS