JSFiddle - React, Tailwind, and code Playground

HTML

<div>
		<ul class="main_nav_bar">
			<li class="first">
				<a href="#">Ссылка</a>
			</li>
			<li><a href="#">Ссылка</a></li>
			<li><a href="#">Ссылка</a></li>
			<li class="last"><a href="#">Ссылка</a></li>
		</ul>
	</div>

CSS

.main_nav_bar li {
    float:left;
    list-style:none;
    vertical-align:center;
}
.main_nav_bar li a {
    padding:20px 50px;
    display:inline-block;
    vertical-align:top;
    background: #ff0090; /* Old browsers */
    background: -moz-linear-gradient(top, #ff0090 0%, #df007e 100%); /* FF3.6+ */
    background: -webkit-gradient(linear, left top, left bottom, color-stop(0%,#ff0090), color-stop(100%,#df007e)); /* Chrome,Safari4+ */
    background: -webkit-linear-gradient(top, #ff0090 0%,#df007e 100%); /* Chrome10+,Safari5.1+ */
    background: -o-linear-gradient(top, #ff0090 0%,#df007e 100%); /* Opera 11.10+ */
    background: -ms-linear-gradient(top, #ff0090 0%,#df007e 100%); /* IE10+ */
    background: linear-gradient(to bottom, #ff0090 0%,#df007e 100%); /* W3C */
    filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#ff0090', endColorstr='#df007e',GradientType=0 ); /* IE6-9 */
}

.main_nav_bar li.first:before {
    width: 0;
    content: " ";
    display: block;
    height: 0;
    float: left;
    border-style: solid;
    border-width: 0px 0px 127px 56px;
    border-color: transparent transparent #007bff transparent;
}
.main_nav_bar li.last:after {
    width: 0;
    content: " ";
    display: block;
    height: 0;
    float: right;
    border-style: solid;
    border-width: 127px 56px 0 0;
    border-color: #007bff transparent transparent transparent;
}