JSFiddle - React, Tailwind, and code Playground

HTML

<input type="radio" name="r" />
<input type="radio" name="r" />

CSS

input[type="radio"]:checked:before {
    content: "";
    display: block;
    position: relative;
    top: 3px;
    left: 3px;
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: red;
}