JSFiddle - React, Tailwind, and code Playground

HTML

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

CSS

.container {
    width: 300px;
    height: 300px;
    /* background-color: red; */
}

.line {
    position: relative;
    z-index: 1;
    left: -50%;
    width: 300%;
    height: 1px;
    background-color: white;
    -webkit-transform: rotate(-45deg); /* Safari and Chrome */
        -ms-transform: rotate(-45deg); /* IE 9 */
            transform: rotate(-45deg);
}