Best thing to do IMHO is to get rid of the scrolling text webpart and use a repeater webpart with a JavaScript and HTML Head webpart for your CSS (if needed). You can define HTML before and after the repeater as well as any kind of HTML within your transformation.
I use this method all the time for different sliders/carousels on websites and it works 100% of the time with any js plug-in because you have total control over the markup. Whereas with the out-of-the-box webpart, it already has it's specific plug-in and requirements which you could configure but much easier to use a repeater.