JSFiddle - React, Tailwind, and code Playground

HTML

<div>
    Рабочий эскиз
</div>

CSS

body {
    font: 16px/18px Times;
}

div {
    border: 1px solid #888;
    padding: 10px;
    background: #EFF8FB;
    position: relative;
    margin:30px;
}

div:before, div:after{content:'';position:absolute;}

div:before{
    left: -1px;
    top: -20px;
    bottom: -20px;  
    border-left: 1px solid #666;
    border-right: 1px solid #666;
    width: 100%;
}
div:after{    
    left: -20px;
    right: -20px;
    top: -1px;
    height: 100%;  
    border-top: 1px solid #666;
    border-bottom: 1px solid #666;
}