SASS for SVG icons with PNG fallback with pure CSS based on: http://www.callmenick.com/2014/04/02/svg-fallback-with-png/

style.scss

@each $icon-name in email, twitter, linkedin {
  @each $color in black, white {
    .icon-#{$icon-name}-#{$color} {
      background: url('../icons/#{$icon-name}-#{$color}.png');
      background-image: url('../icons/#{$icon-name}-#{$color}.svg'), none;
    }
  }
}