In brief
right positions an element relative to the physical right edge according to its positioning mode. On an absolutely positioned button, right: 1rem sets an offset within its containing block.
Useful to know
right positions an element relative to the physical right edge according to its positioning mode. On an absolutely positioned button, right: 1rem sets an offset within its containing block. [1]
This does not automatically mean the end of a line in every language. If a component should follow writing direction, compare the physical rule with a logical offset and check both language directions.
Sources
For further detail and to check the information: