spaces
xxs-responsive (4px)
xs-responsive (8px)
sm-responsive (16px)
md-responsive (32px)
lg-responsive (64px)
xl-responsive (128px)
xxl-responsive (256px)
xxs-fix (4px)
xs-fix (8px)
sm-fix (16px)
md-fix (32px)
lg-fix (64px)
xl-fix (128px)
xxl-fix (256px)
dealing with collapsed margins
d-flex flex-column