JSFiddle - React, Tailwind, and code Playground

HTML

<div class="main">
    <div class="banner"></div>
    <div class="game"></div>
</div>

CSS

.main {
    border: 1px solid red;
    width: 500px;
    height: 500px;
    position: absolute;
}

.banner {
    position: absolute;
    width: 100%;
    height: 100px;
    background: rgba(0,255,0,0.5)
}

.game {
    position: absolute;
    width: 100%;
    bottom: 0;
    left: 0;
    right: 0;
    top: 100px;
    background: rgba(0,0,255,0.5)
}