padding just by pixel, percent is not available. The padding like css rules difference is that instead space you must insert comma.
You use 1,2,3 or 4 numbers for padding, sample:
20,25,45,75When one value is specified, it applies the same padding to all four sides.
When two values are specified, the first padding applies to the top and bottom, the second to the left and right.
When three values are specified, the first padding applies to the top, the second to the right and left, the third to the bottom.
When four values are specified, the paddings apply to the top, right, bottom, and left in that order (clockwise).