JSFiddle - React, Tailwind, and code Playground

HTML

<body>
    <div class="container"><div class="inner"></div></div>
</body>

CSS

* {
    margin: 0;
    padding: 0;
}

html {
    height: 100%;
    /*min-height: 100%;*/
    background: #000;
}

body {
    height: 100%;
    /*min-height: 100%;*/
}

.container {
    height: 100%;
    background: #f00;
    opacity: 0.5;
}

.inner {
    height: 1000px;
    background: #0f0;
    opacity: 0.5;
}