Hello feCastro,
Unfortunately you can’t add directly in content manager as element.
When you create tabs you will need to put html code into tabs.
Code below are example accordination what you can add into your tabs.
<article class="accordion style-1">
<div class="title active">
<a title="Heading 1" href="#tab-11 ">Heading 1</a></div>
<div style="display: block;" class="content">
<p>Our mission is to provide highest quality web solutions at affordable prices with fast delivery and excellent customer service.</p>
</div>
<div class="title ">
<a title="Heading 2" href="#tab-22 ">Heading 2</a></div>
<div style="display: none;" class="content">
<p>Our vision is to increase our market share to 56% till the end of second quartal of 2014, by decreasing delivery time for 15%</p>
</div>
<div class="title ">
<a title="Heading 3" href="#tab-33 ">Heading 3</a></div>
<div style="display: none;" class="content">
<p>By constantly improving quality of our products and hiring more high professional web developers and designers we will increase total product quality by 20%.</p>
</div>
</article>Best regards,
Danijel
