ISBAT have a custom Lightbox background setting

[hacchism]

Is your feature request related to a problem? Please describe.

The Gallery Carousel block currently uses a blurry version of images as background when Lightbox is enabled. Images with a certain type blend into the blurry background and hard to be distinguished.

Describe the solution you'd like

Add an option to add a custom background image to Lightbox.

Additional context/screenshots

Example of the image that blends into a blurry background:

[AnthonyLedesma]

It would be cool to have controls on the LightBox background to make it darker as well as adjust blur levels or maybe even the native zoom for that background.