I can’t seem to reproduce the floating-word problem as long as I use the Courier font: because Courier is a monospaced font, the underscores take as much space as the characters they replace, so if there’s room to fit one variant there’s room to fit the other.
In any case, you can add white-space: nowrap to your Text element’s CSS to prevent it from inserting linebreaks. So you can replace your two .settings.css commands (the .settings prefix is deprecated) with this:
Note that if your page/screen is not wide enough, the text will overflow to the right, forcing your participant to scroll in order to see the end of the text
Let me know if you have questions