JSFiddle - React, Tailwind, and code Playground

HTML

<div class="form_holder">
    <form>
        <input type="text" />
        <input type="submit" />
    </form>
</div>

CSS

.form_holder {
    position: relative;
    margin-left: 17px;
    padding: 1em;

    border: solid 1px #c5c5c5;
    border-radius: 8px;
}

    .form_holder:before {
        content: '';
        position: absolute;
        display: block;
        width: 17px;
        height: 30px;
        background: url('http://s4.gardenersworld.com/forum/images/post-top-left.png');
        left: -17px;
    }