Retina displays

gistfile1.less

@ratio: ''; // default ratio equals to 1
@imagesPath: 'images/';

body {
   background-image: url('@{imagesPath}bg@{ratio}.jpg');
}

@media screen and (-webkit-min-device-pixel-ratio: 2),
  screen and (~`"-o-min-device-pixel-ratio: 2/1"`),
  screen and (min--moz-device-pixel-ratio: 2),
  screen and (-moz-min-device-pixel-ratio: 2),
  screen and (-ms-min-device-pixel-ratio: 2),
  screen and (min-device-pixel-ratio: 2),
  screen and (min-resolution: 192dpi) {
  @ratio: '@2x';
   body {
       background-image: url('@{imagesPath}bg@{ratio}.jpg');
   }
}