CODE EXAMPLE FOR HTML

font awesome change background color stacked

<!-- Create an icon wrapped by the fa-stack class -->
<span class="fa-stack">
    <!-- Change color of the icon that will wrap the number -->
    <span class="fa fa-square fa-stack-2x" style="color:red;"></span>
    <!-- a strong element with the custom content, in this case a number -->
    <strong class="fa-stack-1x">
        1    
    </strong>
</span>