JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container"><div id="line"></div></div>

CSS

#container {
    overflow: hidden;
    width: 50px;
    height: 50px;
    border: 1px solid #aaa
}

#line {
    border: 1px solid #aaa;
    width: 50px;
    height: 85px;
    -webkit-transform: rotate(45deg);
    -moz-transform: rotate(45deg);
    -o-transform: rotate(45deg);
    -ms-transform: rotate(45deg);
    transform: rotate(45deg);
    margin-top: -31px;
    margin-left: -25px;
}