JSFiddle - React, Tailwind, and code Playground

HTML

<body>
    <div id="header">
        <div id="logo">logo</div>
        <div id="menu">menu</div>
    </div>
    <div id="cont">under</div>
</body>

CSS

#header {
    width:200px;
    height:100px;
    outline:solid 1px black;
}
#logo {  display:inline-block;
    width:100px;
    height:100px;
    outline:solid 1px black;
}
#menu {
    display:inline-block;
    width:96px;
    height:96px;
    outline:solid 1px black;
}
#cont {
    outline:solid 1px black;
    width:200px;
    height:300px;
}