MediaWiki:Common.css

/* CSS placed here will be applied to all skins */
#mw-content-container {
        // .background-image-svg( 'images/cat-grey.svg', 'images/cat-grey.png' );
        // background-repeat: no-repeat;
        // background-position: center 15em;
  .background-image-svg ( null, null ) !important;
}