JSFiddle - React, Tailwind, and code Playground

HTML

<div id="red">
    <div id="white">
        <div id="blue"></div>
    </div>
</div>

CSS

div {
    width: 300px;
    height: 300px
}
#red {
    background: red;
    position: relative;
    z-index: -15;
}
#white {
    background: white;
    opacity: 0.5;
    position: relative;
    z-index: -10;
}
#blue {
    background: blue;
    width: 100px;
    height: 100px;
    opacity: 1;
}