Edit in JSFiddle

// open top tab menu
$(document).on('click', '#menu-tab', function () {
    $('#menu-nav').slideToggle('slow');
});

<div id="menu-wrapper">
    <div id="menu-bar"></div>
    <div id="menu-nav">
        <ul>
            <li>Item One</li>
            <li>Item Two</li>
            <li>Item Three</li>
        </ul>
    </div>
    <div id="menu-tab" class="closed">MENU</div>
</div>
<div class="content">
     <h1>HEADING</h1>

    <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut lorem metus, porta ut magna ac, mollis convallis diam. Phasellus tempor eleifend orci at vehicula. Quisque ultrices nibh quis magna consectetur gravida. Vestibulum posuere urna id iaculis varius. Sed non purus vitae dui gravida lobortis id vitae quam. Pellentesque pharetra sed mi et vestibulum. Aenean vel fermentum leo. Aenean vel dignissim magna. In hac habitasse platea dictumst. Vestibulum et odio lectus. In gravida elit sit amet varius convallis. Integer nec enim eget massa cursus fringilla id nec tortor. Sed quis rhoncus est.</p>
</div>

body {
    font-family: Arial, Helvetica, sans-serif;
    font-size: 14px;
    line-height: 25px;
    background-color: #333333;
    color: #D7DADB;
    margin: 0;
}
h1 {
    color: #FFFFFF;
}
.content {
    margin-top: 20px;
    padding: 0 10px;
}
/*__MENU STYLES__*/
 #menu-wrapper {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
}
#menu-bar {
    display: block;
    width: 100%;
    height: 10px;
    background-color: #FC4349;
}
#menu-tab {
    background-color: #FC4349;
    cursor: pointer;
    float: right;
    padding: 5px 10px;
    border-radius: 0 0 5px 5px;
}
#menu-nav {
    display: none;
    padding: 5px 10px;
    background-color: #FC4349;
    color: #333333;
}
#menu-nav ul {
    list-style: none;
    margin: 20px 0 30px;
    padding: 0;
}
#menu-nav ul li {
    padding: 10px;
    border-bottom: 1px solid #E03C41;
    cursor: pointer;
    text-align: center;
}
#menu-nav ul li:first-child {
    border-top: 1px solid #E03C41;
}
#menu-nav ul li:hover {
    background-color: #EB3E44;
}