JSFiddle - React, Tailwind, and code Playground

HTML

<div class="magic">Having trouble</div>

CSS

body {
    background: silver;
}
.magic {
    border-top: 6px solid black;
    background: tomato;
    padding: 10px 40px;
    position: relative;
    margin-bottom: 2px;
}
.magic:before {
    position: absolute;
    bottom: -2px;
    left: 0;
    display: block;
    content:' ';
    width:100%;
    min-height: 1px;
    height: 1px;
    background: tomato;
}