Custom Composer Banner

I have a requirement to add a thin banner to the top of the browser window in Composer.  I'm essentially asking for the same thing as this older post that had no response: https://community.ptc.com/t5/ThingWorx-Developers/Custom-banner-in-Composer/td-p/540405 

Is it possible to configure ThingWorx/Tomcat to display such a banner across all webpages served to users, including Composer?