<link href="//netdna.bootstrapcdn.com/bootstrap/3.1.0/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//netdna.bootstrapcdn.com/bootstrap/3.1.0/js/bootstrap.min.js"></script>
<script src="//code.jquery.com/jquery-1.11.1.min.js"></script>
<div class="container">
<div class="row">
<h5><center>Default Size</center></h5>
<center>
<a href="#aboutModal" data-toggle="modal" data-target="#myModal" class="btn btn-circle btn-primary">C</a>
<a href="#aboutModal" data-toggle="modal" data-target="#myModal" class="btn btn-circle btn-default">I</span></a>
<a href="#aboutModal" data-toggle="modal" data-target="#myModal" class="btn btn-circle btn-info">R</span></a>
<a href="#aboutModal" data-toggle="modal" data-target="#myModal" class="btn btn-circle btn-success">C</span></a>
<a href="#aboutModal" data-toggle="modal" data-target="#myModal" class="btn btn-circle btn-warning">L</span></a>
<a href="#aboutModal" data-toggle="modal" data-target="#myModal" class="btn btn-circle btn-danger">E</span></a>
<br>
<a href="#aboutModal" data-toggle="modal" data-target="#myModal" class="btn btn-circle btn-primary">B</a>
<a href="#aboutModal" data-toggle="modal" data-target="#myModal" class="btn btn-circle btn-default">U</span></a>
<a href="#aboutModal" data-toggle="modal" data-target="#myModal" class="btn btn-circle btn-info">T</span></a>
<a href="#aboutModal" data-toggle="modal" data-target="#myModal" class="btn btn-circle btn-success">T</span></a>
<a href="#aboutModal" data-toggle="modal" data-target="#myModal" class="btn btn-circle btn-warning">O</span></a>
<a href="#aboutModal" data-toggle="modal" data-target="#myModal" class="btn btn-circle btn-danger">N</span></a>
<a href="#aboutModal" data-toggle="modal" data-target="#myModal" class="btn btn-circle btn-primary">S</span></a>
</center>
</div>
<hr>
<div class="col-md-4">
<h5><center>Micro</center></h5>
<center>
<a href="#aboutModal" data-toggle="modal" data-target="#myModal" class="btn btn-circle-micro btn-primary"><span class="glyphicon glyphicon-thumbs-up"></span> </a>
<a href="#aboutModal" data-toggle="modal" data-target="#myModal" class="btn btn-circle-micro btn-default"><span class="glyphicon glyphicon-thumbs-up"></span> </a>
<a href="#aboutModal" data-toggle="modal" data-target="#myModal" class="btn btn-circle-micro btn-info"><span class="glyphicon glyphicon-thumbs-up"></span></a>
<a href="#aboutModal" data-toggle="modal" data-target="#myModal" class="btn btn-circle-micro btn-success"><span class="glyphicon glyphicon-thumbs-up"></span> </a>
<a href="#aboutModal" data-toggle="modal" data-target="#myModal" class="btn btn-circle-micro btn-warning"><span class="glyphicon glyphicon-thumbs-up"></span> </a>
<a href="#aboutModal" data-toggle="modal" data-target="#myModal" class="btn btn-circle-micro btn-danger"><span class="glyphicon glyphicon-thumbs-up"></span> </a>
</center>
</div>