Openlayers Plus tooltips

Is there a way to make the tooltips text appear on a white background? The text gets lost on top of the map detail and other markers and so is barely legible. I'm hoping it is possible to add a white background or failing that, to change the color of the text.

I am by no means an expert on programming, so if there is a place in openlayers_plus_behavior_tooltips.js that I need to go to do this, instructions for a dumby would be much appreciated.

Thank you!
Yanni