RespondTo.scss

@mixin respond-to($viewport-width, $ie-version: 'lt-ie9') {
  @media only screen and (min-width: $viewport-width) {
    @content;
  }
  @if $ie-version == 'lt-ie9' { 
    html.lt-ie9 & { // Using Paul Irish's conditional comments
      @content;
    }
  }
  @else if $ie-version == 'lt-ie8' {
    html.lt-ie8 & { // Using Paul Irish's conditional comments
      @content;
    }
  }
}