body {
  margin: 0;
}

.reftest {
  width: 160px;
  height: 160px;
  background-size:
    160px 40px, 160px 40px, 160px 40px, 160px 40px,
    40px 160px, 40px 160px, 40px 160px, 40px 160px;

  background-position:
    0px 0px, 0px 40px, 0px 80px, 0px 120px,
    0px 0px, 40px 0px, 80px 0, 120px 0;


  background-repeat: no-repeat;
  background-image: url(as-image/red100x100.png),
                    url(as-image/green100x100.png),
                    url(as-image/blue100x100.png),
                    url(as-image/brown100x100.png),
                    url(as-image/red100x100.png),
                    url(as-image/green100x100.png),
                    url(as-image/blue100x100.png),
                    url(as-image/brown100x100.png);
}