JSFiddle - React, Tailwind, and code Playground

by Karim AG

HTML

<div id="test"></div>

CSS

#test {
    widh:300px;
    height:150px;
    background:#C3C3C3;
    position:relative;
    overflow:hidden;
}
#test:after {
    content:'';
    position:absolute;
    right:-100px;
    top:10px;
    transform:rotate(-30deg);
    -webkit-transform:rotate(-30deg);
    -moz-transform:rotate(-30deg);
    -o-transform:rotate(-30deg);
    -ms-transform:rotate(-30deg);
    width:500px;
    height:250px;
    background:#880015;
}