background-size mixin using IE8 polyfill

gistfile1.txt

@mixin ftm-background-size($background-size-value: contain, $background-size-value-y: 100%) {
  $cover-or-contain: ($background-size-value == contain) or ($background-size-value == cover);
  @if $cover-or-contain {
    background-size: $background-size-value;
    -webkit-background-size: $background-size-value;/* Safari 3.0 */
    -moz-background-size: $background-size-value;   /* Gecko 1.9.2 (Firefox 3.6) */
    -o-background-size: $background-size-value;     /* Opera 9.5 */
  } @else {
    background-size: $background-size-value $background-size-value-y;
    -webkit-background-size: $background-size-value $background-size-value-y;/* Safari 3.0 */
    -moz-background-size: $background-size-value $background-size-value-y;   /* Gecko 1.9.2 (Firefox 3.6) */
    -o-background-size: $background-size-value $background-size-value-y;     /* Opera 9.5 */
  }
  -ms-behavior: url(/assets/background_size/backgroundsize.htc);
  // add support for IE8
}