To assign margin related properties using the classes:

.mt-3

- margin-top

.mr-3

- margin-right

.mb-3

- margin-bottom

.ml-3

- margin-left

.mx-3

- margin-left, margin-right

.my-3

- margin-top, margin-bottom

.m-3

- margin-top, margin-bottom, margin-left, margin-right The same for padding properties:

.pt-3

- padding-top

.pr-3

- padding-right

.pb-3

- padding-bottom

.pl-3

- padding-left

.px-3

- padding-left, padding-right

.py-3

- padding-top, padding-bottom

.p-3

- padding-top, padding-bottom, padding-left, padding-right