矢型の矢印 (下向き)のアイコン

<span class="dli-arrow-down"></span>

.dli-arrow-down {
  display: inline-block;
  vertical-align: middle;
  color: #333;
  line-height: 1;
  position: relative;
  width: 0.1em;
  height: 1em;
  background: currentColor;
}

.dli-arrow-down::before {
  content: '';
  width: 0.65em;
  height: 0.65em;
  border: 0.1em solid currentColor;
  border-top: 0;
  border-right: 0;
  transform: rotate(-45deg);
  transform-origin: bottom left;
  position: absolute;
  left: 50%;
  bottom: -0.05em;
  box-sizing: border-box;
}