$os-icons: "/assets/images/icons/os-icons.png";

%os-icons {
  background: url($os-icons) 0 0 no-repeat;
  @include background-size(auto 15px);
  display: inline-block;
  height: 15px;
  width: 15px;
}
.mac-icon {
  @extend %os-icons;
  background-position: -35px 0;
}
.windows-icon {
  @extend %os-icons;
}
.linux-icon {
  @extend %os-icons;
  background-position: -65px 0;
}
.paid-icon {
  @extend %os-icons;
  background-position: -100px 0;
}