JSFiddle - React, Tailwind, and code Playground

HTML

<ul id="folders">
    <li class="add"><span></span></li>
</ul>

CSS

ul#folders {
    margin: 20px;
    padding: 0;
    list-style: none;
}

    ul#folders li
    {
        margin: 0 20px 15px 0;
        padding: 15px;
        display: inline-block;
        height: 190px;
        width: 220px;
        list-style: none;
        background-color: #F7F7F7;
        border: 1px solid #CDD2D6;
        border-radius: 6px;
        color: #A9AEB2;
        cursor: pointer;
        box-shadow: 0 4px 6px #F7F7F7;
        vertical-align: top;
        text-align: center;

        -moz-transition: background-color 0.2s, color 0.2s, background-position 0.2s;
        -o-transition: background-color 0.2s, color 0.2s, background-position 0.2s;
        -webkit-transition: background-color 0.2s, color 0.2s, background-position 0.2s;
        transition: background-color 0.2s, color 0.2s, background-position 0.2s;
    }

        ul#folders li:hover {
            background-color: #FBFBFB;
        }

        ul#folders li.add span {            
            display: block;
            width: 26px;
            height: 26px;
            background-color: green;
            vertical-align: middle;
        }