( center a single element vertically and horizontally )
data-center
( center multiple elements vertically )
data-mvcenter
data-mvcenter
data-mvcenter
( center multiple elements horizontally )
data-mhcenter
data-mhcenter
data-mhcenter
( center a single element vertically )
data-vcenter
( center a single element hotizontally )
data-hcenter
data-hcenter
data-vcenter