JSFiddle - React, Tailwind, and code Playground

HTML

<body>
<div class="container">
    <div id="top">top</div>
    <div id="left">left</div>
    <div id="right">
        <div id="sub-header">subheader</div>
        <div id="content-area">
            <div id="alert">alert!</div>
            <div id="content">content<br /><br /><br /></div>
        </div>
    </div>
    
</div>
<body>

CSS

body {
    height: 100%;
    overflow: hidden;
}
#top{
    position: absolute;
    background: yellow;
    height: 50px;
    width: 100%;
    top: 0;
}
#left {
    background: #e3e3e3;
    position: absolute;
    bottom: 0;
    left: 0;
    top: 50px;
    width: 200px;
}

#right {
    position: absolute;
    bottom: 0;
    left: 200px;
    right: 0;
    top: 50px;
}
#sub-header {
    height: 20px;
    background: orange;
}
#content-area {
    position: absolute;
    top: 20px;
    right: 0;
    bottom: 0;
    left: 0;
    overflow-y: auto;
}
#alert {
    background: red;
    color: white;
}
#content {
    width: 100%;
    float: left;
}