JSFiddle - React, Tailwind, and code Playground

HTML

<label>
    <input type = "text" required/><span></span>
</label>

CSS

@font-face {
    font-family: 'Font Awesome';
    src: url('https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.4.0/fonts/fontawesome-webfont.woff') format('woff');
    font-weight: normal;
    font-style: normal;
}

label {
    display: inline-block;
    position: relative;
}

label > input {
    height: 25px;
    font: normal 14px/25px Sans-Serif;
    padding: 0 25px 0 10px;
    border-radius: 5px;
    border: 1px solid #aaa;
    outline: 0;
}

label > input:required + span:before {
    content:"\f069";
    font: normal 14px/1 "Font Awesome";
    color: red;
    position: absolute;
    bottom: 50%;
    right: 5px;
    transform: translateY(50%);
}