» First and foremost, we will create sample HTML structure and assume that the `selector` class exists.

<div class="selector">
	<div>
	  <div>
		<div>
		  <div class="e-n-tab-title" aria-selected="true">Tab 1</div>
		  <div class="e-n-tab-title" aria-selected="false">Tab 2</div>
		  <div class="e-n-tab-title" aria-selected="false">Tab 3</div>
		</div>
	  </div>
	</div>
</div>

» Use combination of CSS selector and an attribute selector.

selector > div > div > div > .e-n-tab-title[aria-selected="true"] {
    background: red;
}