Gallery image alignment

Hello,

First of all I wanted to thank you for Voltata theme, it is great and I really like how customizable it is. My only problem with it has been the gallery, more specifically the alignment of pictures in the large setting. I expect the behaviour to be something along these lines:
https://antbaena.tumblr.com/tagged/inspiration
where the pictures get resized to a certain width in order to fit into specified columns and height is adjusted to keep the pictures in correct ratio; then pictures simply align to equal distance away from each other. Instead of this behaviour I get this:
https://5ille.com/wps/gallery-example2.jpg
where the column on the right behaves as expected (bottom image should be aligned on the left if this was working correctly). The right side also seems to be determining how the pictures are aligned in other columns height wise. The second picture on the mid column should be higher but seems to be aligned to the same height as the second picture in the right hand side column.

I am developing the site locally using AMPPS. The picture has been taken from Firefox, but I get the same behaviour on Chrome. I have Voltata 1.2.1.

Do you think there is an easy fix for this (I know CSS, but the behaviour of the gallery seems to be controlled by PHP) or can you perhaps do an update to Voltata that could fix this?

Thank you!