JSFiddle - React, Tailwind, and code Playground

HTML

<div>
<div class="main"></div>
</div>
 <div>
<div class="main"></div>
</div>

CSS

.main:before {
    box-shadow: -15px 0 15px -15px inset;
    content: " ";
    height: 100%;
    left: -15px;
    position: absolute;
    top: 0;
    width: 15px;
}
.main:after {
    box-shadow: 15px 0 15px -15px inset;
    content: " ";
    height: 100%;
    position: absolute;
    right: -15px;
    width: 15px;
}
.main {
    background: none repeat scroll 0 0 #EEEEEE;
    height: 100px;
    margin: 50px;
    position: relative;
    width: 100px;
}