//
// e.g. .my-nav { @include affix(); }
//
@mixin affix {
  &.fixed-top {
    left: 0;
    position: fixed;
    top: 0;
  }
}

//
// e.g. .my-content { @include affix-buffer(300px); }
//
@mixin affix-buffer($buffer-size) {
  &.fixed-top-buffer {
    margin-top: $buffer-size;
  }
}