JSFiddle - React, Tailwind, and code Playground

HTML

<html>
    <head>
        <link rel=stylesheet href="style.css" type="text/css" media=screen>
        <title>Demo</title>
    </head>
    <body>
        <div id="container">
            <div id="header"></div>
            <div id="menu">
                <div class="right"></div>
                <div class="left">
                    Item 1 - Item 2 - Item 3
                </div>
            </div>

        </div>
    </body>
</html>

CSS

body {
    padding: 0px;
    margin: 0px;
}

#container {
    width: 100%;
    text-align: center;
    background: #8080ff;
    overflow: hidden;
}

#header {
    width: 990px;
    height: 200px;
    background-color: #4040ff;
    margin: 0 auto;
}

#menu {
    margin-right: -495px;
    float: right;
    overflow: auto;
    height: 30px;
    width: 100%;
    margin-top: -130px;
    display: inline-block;
}

#menu .left {
    width: auto;
    height: 30px;
    background: white;
    float: right;
}

#menu .right {
    width: 50%;
    height: 30px;
    background: white;
    float: right;
}