@asset_path1: 'assets/';
@url1: '/assets/@{asset_path1}/images/logo.png';
.test{ background:url(@url1); }


@asset_path2: 'assets';
@url2: '/assets/@{asset_path2}/images/logo.png';
.test{ background:url(@url2); }


.test{ background:url('http://domain/@{asset_path2}/images/logo.png'); }