kind: content 1em
Kind for “smart” content paddings. Accepts one to four units as params (like
margin), then creates paddings for the sides, but in a way the both and bottom paddings would be collapsing, so they would be overlapped by inner elements' margins.
Elements for collapsing helpers
By default the collapsing paddings are created using the pseudos (except IE where the ordinal non-collapsing paddings are used), if you'd want to use it on the actual other elements, use the proper
kind: content 1em (-after '&-helper')
If you don'w want a collapsing padding from any side, you can override the element to the empty one, in this case this side would get its padding.
kind: content 1em (-before '')