JSFiddle - React, Tailwind, and code Playground

HTML

<div class="fix-me"><div>I'm a box like a box should be with this kind of border-settings...</div></div>

CSS

.fix-me { 
    border-top:30px solid green;
    height:200px;
    width:200px;
}
.fix-me div{
    border:10px solid red;
    border-top:0;
    padding:5px;
    height:100%;
}