Breakpoint targetable classes
Any breakpoint targetable class may have the shortname of the desired breakpoint added as a suffix. This class will apply at the supplied breakpoint and up. Valid suffixes are: sm (480px), md (768px), lg (992px), xl (1200px). No prefix is the default and should be treated as xs mobile.
Specific breakpoint classes are also available with -only
appended (sm-only, md-only, lg-only, xl-only).
.{breakpoint-targetable-class}@{sm[-only],md[-only],lg[-only],xl[-only]}
The following will be 1 column on mobile and 4 columns at md and up.
.flex__container--1-up.flex__container--4-up@md