gistfile1.sass

// Assumes you want IE 8 and below to use largest screen size
@mixin respond-to($viewport-width, $fallback: false, $ie-version: 'lt-ie9') {
  @media only screen and (min-width: $viewport-width) {
    @content;
  }
  @if $fallback == true {
    @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;
      }
    }
  }
}