JSFiddle - React, Tailwind, and code Playground

HTML

<div id="outer">
    <div>
        <div id="middle">
            <div>Hello</div>
            <div>OK</div>
            <div id="inner">
                <embed>text</embed>
            </div>
        </div>
    </div>
</div>

CSS

body, html {
    height: 100%;
}
#outer {
    background-color: green;
    height: 100%;
}

#middle {
    background-color: blue;
}

#inner {
    background-color: red;
    height: 100%;
}
embed {
    height: 100%;
}