JSFiddle - React, Tailwind, and code Playground

HTML

<ul class="topMenu">
				<li><a href="#">Автосалон</a></li>
				<li><a href="#">Путешествия</a></li>
				<li><a href="#">История</a></li>
				<li><a href="#">Разное</a></li>
			</ul>

CSS

.topMenu{
	position: absolute;
	right: 0;
	bottom: 0;
	background-color: #000;
	padding: 10px 12px 10px 0;
}
.topMenu li{
	display: inline;
	margin-left: 20px;
}
.topMenu li a{
	color: #fff;
}
.topMenu:before{
    content: "";
    display: block;
    position: absolute;
    top: 0;
    left: 0;
    border-top: 0 solid #fff;
    border-right: 0 solid transparent;
    border-bottom: 40px solid transparent;
    border-left: 20px solid #fff;
}