.yu-center {
  position: relative;
  width: 100%;
  height: 100%; }
  .yu-center .center {
    width: 300px;
    height: 300px;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%); }
    .yu-center .center.large {
      width: 400px;
      height: 400px; }
    .yu-center .center.big {
      width: 500px;
      height: 500px; }