m - for classes that set margin, like this :
mt - for classes that set margin-topmb - for classes that set margin-bottomml - for classes that set margin-leftmr - for classes that set margin-rightmx - for classes that set both margin-left and margin-rightmy - for classes that set both margin-top and margin-bottomWhere size is one of margin :
0 - for classes that eliminate the margin by setting it to
0, like mt-01 - (by default) for classes that set the margin to
$spacer * .25, like mt-12 - (by default) for classes that set the margin to
$spacer * .5, like mt-23 - (by default) for classes that set the margin to
$spacer, like mt-34 - (by default) for classes that set the margin to
$spacer * 1.5, like mt-45 - (by default) for classes that set the margin to $spacer * 3, like mt-5auto - for classes that set the margin to auto, like mx-auto