grid(cellsize = 0.3rem, color = $c-grid)
  &
    background-size cellsize cellsize
    background-image linear-gradient(to right, color 1px, transparent 1px),
                     linear-gradient(to bottom, color 1px, transparent 1px)

left-stripes(color, offset = -1.5rem)
  &
    position relative
  &:before
    content ''
    position absolute
    top 0
    left offset
    bottom 0
    height 100%
    width 0.3rem
    border solid color
    border-width 0 0.2rem 0 0.6rem

square()
  &
    position relative
  &:before
    content ''
    position absolute
    width 0.7rem
    height 0.7rem
    background-color $c-strong
    {block}