Layerslider WP

Hi Kriesi
I am having an issue with the Layerslider text layers.
I am able to add text and to change the colour but the size of the font doesn’t change unless I make the content information have a <span> class around it to change it inline.
The problem then is that it doesn’t change for mobile devices. I need to make sure the text is the right size on larger views but react well on smaller devices.
You can see on the link below
Slides 1-3 have the span class in the content so show at the right size (but are not responsive), I have removed this for Slide 4 which, although it is the right size in the styles, doesn’t display as required.
Please advise.
Many thanks
Helen