Bootstrap 4 cheatsheet
a - all
t - top
b - bottom
l - left
r - right
x - left and right
y - top and bottom
m-t = margin-top: 1em
m-t-md = margin-top: 1.5em
m-t-lg = margin-top: 3em
m-a-0 = margin: 0;
Padding is same but with `p` at the front
`hidden-sm-down` = Hides from sm down (sm and xs)
`hidden-sm-up` = Hides from sm up (sm, md, lg)
clearfix
center-block
pull-left = float left
pull-right = float right
text-left = text-align: left
text-md-left = for md and up
text-right
text-center
text-justify
text-nowrap
text-truncate
text-lowercase
text-uppercase
text-capitalize
text-muted = makes it lighter grey