JSFiddle - React, Tailwind, and code Playground

HTML

<div class="g">
    <div>bla</div>
</div>

CSS

.g {
    border-right-width:1px;
    -webkit-border-image: -webkit-gradient(linear, 0 0, 0 100%, color-stop(0, transparent), color-stop(0.5, grey), color-stop(0.5, grey), color-stop(1, transparent)) 0 100%;
    border-right-width: 1px;
    border-left-width: 0px;
    border-top-width: 0px;
    border-bottom-width: 0px;
    padding: 2px;
    width: 400px;
    height: 150px;
    margin: 10px auto;
}
.g > div { /*background: #fff; */}