JSFiddle - React, Tailwind, and code Playground

HTML

<div class="left-dash">
  <div class="dash-stats-3">
	  	<ul class="dash-stats-3-ul">
			<li><span id="explore-themes">testing</span></li>
			<li>
				<a href="#" class="tab-link" data-remote="true">
					<span class="ss-pika ss-icon">1</span><span class="theme"> test-1</span>
				</a>
			</li>
			<li>
				<a href=#"" class="tab-link" data-remote="true">
					<span class="ss-pika ss-icon">2</span><span class="theme"> test-2</span>
				</a>
			</li>
			<li>
				<a href="" class="tab-link" data-remote="true">
					<span class="ss-pika ss-icon">3</span><span class="theme"> test-3</span>
				</a>
			</li>
			<li>
				<a href="/theme/inspiring" class="tab-link" data-remote="true">
					<span class="ss-pika ss-icon">4</span><span class="theme"> test-4</span>
				</a>
			</li>
			<li>
				<a href="#" class="tab-link" data-remote="true">
					<span class="ss-pika ss-icon">5</span><span class="theme"> test-5</span>
				</a>
			</li>
		</ul>
	</div>
</div>

CSS

.left-dash {
    background: #444;
    height: 500px;
}
.left-dash div {
  -webkit-border-radius: 4px 4px 4px 4px;
  border-radius: 4px 4px 4px 4px;
}
.left-dash div ul li:first-child, .left-dash div ul li:first-child a {
  -webkit-border-radius: 4px 4px 0px 0px;
  border-radius: 4px 4px 0px 0px; 
}

.left-dash div ul li:last-child,
.left-dash div ul li:last-child a {
  -webkit-border-radius: 0px 0px 4px 4px;
  border-radius: 0px 0px 4px 4px; 
}



.dash-stats-3 {
	width: 220px;
	margin-bottom: 17px;
	background: #9f9f9f;
	-webkit-background-clip: padding-box; /* for transparent border with solid bg - Safari */
	background-clip: padding-box;/* for IE9+, Firefox 4+, Opera, Chrome */
	border-radius: 0px;
	border: 1px solid rgba( 0, 0, 0, 0.15);
	box-shadow: inset 0px 0px 2px 0px #FFFFFF,0px 1px 3px 0px rgba(0,0,0, 0.15);
	-webkit-box-shadow: inset 0px 0px 2px 0px #FFFFFF,0px 1px 3px 0px rgba(0,0,0, 0.15);
	-moz-box-shadow: inset 0px 0px 2px 0px #FFFFFF,0px 1px 3px 0px rgba(0,0,0, 0.15);
	-o-box-shadow: inset 0px 0px 2px 0px #FFFFFF,0px 1px 3px 0px rgba(0,0,0, 0.15);
	font-family:'Museo Sans W01 700' san-serif;
	font-size: 14px;
	color: #828282;
	text-shadow: 0px 1px 1px #FFFFFF;
	font-weight: normal !important;
}



.dash-stats-3 ul li a, .dash-stats-3 ul li:first-child {
	height: 41px;
	border-bottom: solid rgba( 0, 0, 0, 0.15) 1px;
	border-top: solid rgba(255, 255, 255, .65) 1px;
}
.left-dash div ul li:last-child, .left-dash div ul li:last-child a {
	border-bottom: none;
}

.dash-stats-3 ul li a {
	position:relative;
	line-height:43px;
	display:block;
}






.dash-stats-3 ul li a.active-tab {
	z-index:120;
	border-top: 1px solid #5b82a7;
	background: #4e81be; /* Old browsers */	
}

JavaScript

$(function(){
        $('a.tab-link').click(function(){
          $('a.tab-link').removeClass('active-tab')
          $(this).addClass('active-tab')
        });
      });