Transparent labels drag & drop labelling

Dear all,

I use the page type Drag and Drop labelling. Is it possible to make the background of the labels transparent instead of white? I would like to place an image of a colored lens in the title field and let the students drag & drop the lens at an image of the eye.

Add an optional styles property and then add something like the following: The above is basically removing the default background, border and shadow.
HTH
Ron

Thanks Ron!