JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
    <div class="circle">11</div>
</div>

CSS

.container {
    background-color: grey;
    height: 200px;
}
.circle {
    width: 20px;
    height: 20px;
    border-radius: 12px;
    border: 1.5px solid #000;
    font-family: Cambria;
    font-size: 11px;
    color: white;
    line-height: 20px;
    text-align: center;
    background: #fff;
    position: relative;
    z-index: 1;
}
.circle:before {
    position: absolute;
    right: 2px;
    top: 2px;
    left: 2px;
    bottom: 2px;
    content: '';
    background: #3E78B2;
    border-radius: 25px;
    z-index: -1;
}
.circle:hover {
    width: 27px;
    height: 27px;
    border-radius: 18px;
    font-size: 12px;
    color: white;
    line-height: 27px;
    text-align: center;
    background: #fff;
}