Padding Differentiation

Question

What is the padding differentiation between padding=5px; and padding=5 5 0px;?

Answer 1

First one tells that padding should be 5 pixels forr every element side.
Second one tells that padding should be 5 unknown measure units from all element sides, but for bottom side it should be 0 pixels. This rule is badly written. You should write it like 5px 5px 0 if you want pixel units of course.

Answer 2

thank you for your explanation.