As far as I know, Visual Composer doesn’t have border in CSS. It would need to be overwritten in Custom CSS or create a separate class that you can add to this particular text shortcode from the visual composer settings.
Unfortunately I don’t have any links from Visual Composer for this specific question. But I tried to make this for you as example based on VC settings.
Firs, add a new class in style.css or in Design – Custom CSS
border: 1px solid #f0f0f0;
padding: 13px 13px 9px 13px;
-webkit-box-shadow: 0px 2px 0px 0px rgba(227, 228, 231, 1);
box-shadow: 0px 2px 0px 0px rgba(227, 228, 231, 1);
You can edit the CSS settings.
Then, when you add the Visual Composer shortcode, text – you have there Extra class name
This should do it.