_clearfix.sass

=clearfix
  overflow: hidden
  +has-layout

/* clears while allowing overflow (great for use with box shadows)
=pie-clearfix
  &:after
    content: " "
    display: block
    height: 0
    clear: both
    overflow: hidden
    visibility: hidden
  +has-layout

=has-layout
  // This makes ie6 get layout
  display: inline-block
  // and this puts it back to block
  &
    display: block