Unfortunately if I try to change the zoom on my browser to make everything fit in my screen, UI elements don't get scaled like they should and end up being too large and unreadable. If you try changing your browser zoom while playing, you might see that too.
I know there's a way to change that behavior in Godot but I haven't had to mess with it in Unity; it looks like there's a Canvas Scaler component where you can change the UI Scale Mode, and maybe it should be Scale with screen size if it's not already, but I don't have a Unity project at the moment where I can test it out myself.