How to hide title bar for a specific window?

I am running Linux Mint 18.3 with Gnome 3.18 as my desktop. I have been building a loading screen for an application I have installed (Mycroft AI). I have the animation, I have it pop up on loading, i have it closing as soon as it finishes loading. What I DO NOT have is a loading screen with no title bar (what I have is in the screen shot below). As you can see, i still have the title bar. How do I remove it? The fewer apps I have to install to get this to work, the better. Thanks in advance!