This paragraph has a bottom margin of 0 (zero).

This paragraph has a top margin of 0 (zero).

This paragraph has a bottom margin of 0.75em (three-quarters of an em).

This paragraph has a top margin of -1em (negative one em).

This paragraph has a bottom margin of -0.75 (negative three quarters of an em).

This paragraph has a top margin of 0 (zero).