Background colour/font on slideshow

Hi, new user so please bear with me… I can't seem to change the background when viewing photos full screen - it is black whatever the theme I choose. If I can't change the background, can I change the font on the photo sub-title. The filename shows up in bold white, so that's OK, but the sub-titles hardly show against the black background. I really need the subtitles to give the voter information on the photo they are viewing.
Thanks.

Hello and welcome to PollUnit. You cannot change the colors of the lightbox. But we will take a look at it and make some optimizations. I will get back to you here.

We have improved the readability of the subtitle in the lightbox.

Thankyou :)