JSFiddle - React, Tailwind, and code Playground

HTML

<div class="image"></div>

CSS

.image {
    width: 200px;
    height: 200px;
    position: relative;
    margin:20px 0px 0px 20px;    
    background: #eee;
    bottom: 1px solid  #333;
}
 
    .image:before {
         content:'';
        position:absolute;
       top: -5px;
       left: -5px;
        width: 0px;
        height: 0px;
        border-style: solid;
        border-width: 30px 30px 0 0;
        border-color: #cae2fc transparent transparent transparent;
      
}
    .image:after {
        content:'';
        position:absolute;
        right: -5px;
        bottom: -5px;
       width: 0px;
        height: 0px;
        border-style: solid;
        border-width: 0 0 30px 30px;
        border-color: transparent transparent #cae2fc transparent;
    }