I have embedded a VideoAsk on my website but the button text is invisible.

In the VideoAsk builder, the buttons look a little better but this is not how they render when I play the VideoAsk in my site.

This article has some vague instructions for customising VideoAsks, but it’s not clear about what the Primary, Secondary and Background colours are referring to. https://www.videoask.com/help/branding/360050487192-create-default-videoask-settings
I need to see the background colour of my button to something dark. I need to set the font colour of my button to something bright. I need sufficient contrast between them so that they text is readable.
I don’t care much about the colour of the button letter and its circle. Reading the letter is not very important to my visitors.
Can anyone guide in in the right direction to set the button background and font colours?
Thanks, Neil