background-color: #fff
color: $blue
border-radius: 50%
padding: 5px 5px
<span class="fa-stack fa-lg">
<i class="fa fa-square-o fa-stack-2x"></i>
<i class="fa fa-twitter fa-stack-1x"></i>
</span>
<span class="fa-stack fa-lg">
<i class="fa fa-circle fa-stack-2x"></i>
<i class="fa fa-flag fa-stack-1x fa-inverse"></i>
</span>