JSFiddle - React, Tailwind, and code Playground

HTML

<div class="line">
    <div class="info"></div>
</div>
<div class="box"></div>

CSS

body {
    margin: 50px;
}

.box {
    background: grey;
    width: 500px;
    height: 40px;
    z-index: 10;
    position: relative;
}

.line {
    background: blue;
    width: 500px;
    height: 5px;
    z-index: 9;
    position: relative;
    top: 0;
    overflow: visible;
}

.line .info {
    width: 50px;
    height: 25px;
    background: red;
}