SOURCE

<div class="badge">1</div>
<div class="badge">5</div>
<div class="badge">99</div>
<div class="badge">999</div>

.badge{
  position: relative;
  display:inline-block;
  padding: 10px;
  line-height:1;
	color: #fff;
	font-size:14px;
}
.badge:before{
  content: '';
  position:absolute;
  width:100%;
  padding-top:100%;
  background:#ffb403;
  z-index:-1;
  left: 0;
  top:50%;
  transform:translateY(-50%);
  border-radius:50%;
}