code: function borderOffset ({ borderBottomWidth, borderTopWidth }, boxModelRules) {
    const offsets = {}
    if (borderTopWidth) {
      offsets.position = 'relative'
      offsets.top = boxModelRules.top || 0 - borderTopWidth
      offsets.marginBottom = parseInt(boxModelRules.marginBottom || 0, 10) -
        borderTopWidth
    }
    if (borderBottomWidth) {
      offsets.position = 'relative'
      offsets.marginBottom = (offsets.marginBottom ||
        boxModelRules.marginBottom ||
        0) - borderBottomWidth
    }
    return {
      ...boxModelRules,
      ...offsets
    }
  }
docs: /*
  Offsets the element to compensate for the border width by subtracting the
  vertical border widths from the vertical positioning values. This provides
  the benefit of re-aligning the element's content to the grid and forcing the
  border to lay *outside* the grid. Using relative positioning allows these
  offsets to work better when margin collapsing is at play.