JSFiddle - React, Tailwind, and code Playground

HTML

<nav>
    <ul>
        <li><a href="#">Home</a></li>
        <li><a href="#">Services</a></li>
        <li><a href="#">Contact</a></li>
    </ul>
</nav>

CSS

nav ul{
    list-style: none;
}

nav ul li{
    float:left;
    margin-right:20px
}
nav ul li a{
    padding: 10px 20px;
    background: #4579bd;
    color: white;
    text-decoration: none;
    position: relative;
    z-index:11;
}

nav ul li a:before{
    width: 0;
    height: 0;
    border-top: 19px solid transparent;
	border-left: 19px solid #4579bd;
	border-bottom: 19px solid transparent;
    position:absolute;
    top:0px;
    left:100%;
    content: ' ';
}