https://www.w3.org/TR/css3-positioning/#logical-box-offsets-beaso

Warning: this property depends on writing-mode support to behave as intended.

This is a paragraph. It should be offset two (2) em from the bottom of its containing block.

This is a paragraph. It should be offset two (2) em from the left of its containing block.

This is a paragraph. It should be offset two (2) em from the right of its containing block.