An experiment with a tinted background and IE8 flag similar to the Guardian's media queries one. In the case of not using Modernizr and having a seperate IE8 and below stylesheet.

tinted-background.scss

$IE8:false;
@mixin tinted-black(image) {
 @if ($IE8 == false) {
  background: 
    /* top, transparent red, faked with gradient */ 
    linear-gradient(
      rgba(0, 0, 0, 0.45), 
      rgba(0, 0, 0, 0.45)
    ),
   
  }
  else {
   background:  url(image);
  }
}