JIG works quite fine with custom lightboxes, usually a single line is all that's needed, like in the case of iLightBox in the Avada theme.
Choose Custom Lightbox in JIG Settings > Lightboxes tab > Lightbox type (also for mobile) (screenshot).
Add this to the Custom lightbox JS call setting:
No, because Justified Image Grid adapts to the font used by your theme. It's best to be consistent about fonts. Let the theme manage the content font and subsequently, how the gallery captions look like. There are no font-family CSS rules in JIG.
In case your theme doesn't come with an option to use Google Fonts, [...]
Justified Image Grid itself doesn't offer any bulk upload tools. There is a simple reason, this is not a gallery management plugin, but a display. On the other hand, it uses content sources where FTP upload in bulk is possible or can be achieved easily.
WordPress doesn't have an out of the box solution to bulk [...]
Yes, but please note that it's not Justified Image Grid that handles frontend uploading. It's not a source by itself and does not manage images, but shows content from various sources. With that said, it simply uses the fact that certain frontend upload solutions are clever enough to attach images to posts. JIG can automatically [...]