複製のアイコン

<span class="dli-clone"></span>

.dli-clone {
  display: inline-block;
  vertical-align: middle;
  color: #333;
  line-height: 1;
  width: 0.9em;
  height: 0.9em;
  border: 0.1em solid currentColor;
  border-radius: 0.1em;
  background: #fff;
  box-sizing: content-box;
  position: relative;
  box-shadow: -0.2em 0.2em 0 -0.1em #fff, -0.2em 0.2em 0 0 currentColor;
}