JSFiddle - React, Tailwind, and code Playground

HTML

<body>
    <div>
        <ul class="header flex-container">
            <li class="nav flex-item">About</li>
            <li class="nav flex-item">Links</li>
            <li class="nav flex-item">Contact</li>
        </ul>
    </div>


    <div class="content flex-container">
        <div class="sidebar flex-item">Sidebar</div>
        <div class="main flex-item">
        This is the content<br />
        This is the content<br />
        This is the content<br />
        This is the content<br />
        </div>
        <div class="sidebar flex-item">Sidebar</div>
        
    </div>
    <footer>footer here</footer>
</body>

CSS

body{
    margin: 0px;
    font-family: sans-serif;
}

.flex-container{
    /* flexbox properties*/
    display: -webkit-flex;
    -webkit-flex-direction: row;
}

.flex-item{
    /*flexbox properties*/
    display: -webkit-flex;
    align-items: center;
    justify-content: center;
}

.header{
    height: 50px;
    background-color: tomato;
    margin: 0;
    border-bottom: 3px solid rgba(0,0,0,0.3);
}

ul{
    justify-content: flex-end;
}

.nav{
    flex-direction: row;
    margin: 2px;
    padding: 0 10px 0 10px;
    background-color: rgba(0,0,0,0.2);
    color: white;
}

.content{
    height: 300px;
    margin: 0;
}

.sidebar{
    background-color: grey;
    flex: 1;
}    

.main{
    background-color: lightgrey;
    flex: 2;
}

footer{
    height: 50px;
    border-top: 3px solid rgba(0,0,0,0.3);
    background-color: tomato;
}