チェック（丸囲み）のアイコン

<span class="dli-check-circle"><span></span></span>

.dli-check-circle {
  display: inline-block;
  vertical-align: middle;
  color: #333;
  line-height: 1;
  position: relative;
  width: 1em;
  height: 1em;
  border: 0.1em solid currentColor;
  border-radius: 50%;
  box-sizing: content-box;
}

.dli-check-circle > span {
  width: 0.58em;
  height: 0.261em;
  border: 0.1em solid currentColor;
  border-top: 0;
  border-right: 0;
  box-sizing: border-box;
  transform: translateY(-25%) rotate(-45deg);
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  margin: auto;
}