JSFiddle - React, Tailwind, and code Playground

HTML

Content...<br>
Content...<br><br>
<div id='outer'>
    <div class='box' id='first'></div>
    <div class='box' id='second'></div>
</div>

CSS

body {
    background-color: #ddd;
}

#outer {
    position: relative;
    border: 1px solid green;
}

.box {
    width: 64px;
    height: 64px;
    opacity: 0.5;
}

#first {
    background-color: red;
}

#second {
    position: absolute;
    top: 0px;
    left: 0px;
    background-color: blue;
}