<!-- Plain Extra Small Icons: -->
    <span class="plain-icon icon-xs mr-2 mb-2">
      <i class="fa fa-user"></i>
    </span>

    <!-- Bordered Extra Small Icon: -->
    <span class="outline-icon icon-xs mr-3 mb-3">
      <i class="fa fa-user"></i>
    </span>

    <!-- Backgrounded Extra Small Icons -->
    <span class="fill-icon icon-xs mr-3 mb-3">
      <i class="fa fa-user"></i>
    </span>

    <!-- Backgrounded & Bordered Extra Small Icons -->
    <span class="fill-outline-icon-inner">
      <i class="fa fa-user"></i>
    </span>