perfect circle in css with border-radius doesn't work

Here is a JSfiddle with some changes:

JSFiddle for round badge

The main changes are:

padding: 0px;
width: 50px;
height: 50px;
line-height: 50px;

Having a line-height equal to the container height will center the text vertically. This only works if the text fits on a single line.

Edit: (copied code from JSFiddle)

.badge {
    display: inline-block;
   
    padding: 0;
    width: 50px;
    height: 50px;    
    line-height: 50px;
    
    font-size: 12px;
    font-weight: lighter !important;
    color: #fff !important;
    text-align: center;
    white-space: nowrap;
    vertical-align: baseline;
    background-color: #d73d33;
    border-radius:50px;
    position: relative;
    top: -3px;
}

<span class="badge badge-success">8</span>

if it's not perfect circle check display: inline-block and border-radius: 50%:

 .cirlce {
    height: 20px;
    width: 20px;
    padding: 5px;
    text-align: center; 
    border-radius: 50%;
    display: inline-block;
    color:#fff;
    font-size:1.1em;
    font-weight:600;
    background-color: rgba(0,0,0,0.1);
    border: 1px solid rgba(0,0,0,0.2);
    }