Editing target of vantage siteorigin attribution link

We updated our website with the Vantage theme. It is providing us with exactly the look and functionality we wanted, and are happy to continue sharing a SiteOrigin attribution link with our web audience. We would, however, like to have users of the attribution link open the SiteOrigign website in a “blank” browser window, so that they can easily return to our Chorale website. Is their a CSS snippet that will allow this on all pages of our new site?