Custom layout for form success message?

I have a View for my custom form.

In the view I have the following section:

<%-- area for showing Form's status or validation --%><divclass="container roi"><divclass="Form__Status bg-pattern parallax-background"><div class="Form__Status__Message <%: statusDisplay %>" data-f-form-statusmessage><divclass="row"><divclass="col-md-12"><h3>Vielen Dank!</h3><divclass="row success-msg"><divclass="col-xs-3 center-block-xs col-sm-push-0 col-md-2"><divclass="square mb-1"><divclass="square-content circle bg-red"><imgclass="icon-centered"src="/Static/img/icons/icon_check_white.svg"alt=""></div></div></div><divclass="col-xs-12 col-sm-9 col-md-10"><pclass="mt-1">Übermittlung erfolgreich pp. </p><pclass="mt-1"style="color:red;"><%= message %> </p></div></div></div></div></div></div></div>

However when I test the form in my browser the success message looks like this:

<divclass="container roi"><divclass="Form__Status bg-pattern parallax-background"><divclass="Form__Status__Message Form__Success__Message"data-f-form-statusmessage="">Übermittlung erfolgreich.</div></div></div>

It appears that EPiServer is modifying this and pasting it's own success message. How can I add a custom layout for the success message?