Steps to replicate the issue (include links if applicable):

• Create a packed gallery.
• Open it. E.g.: https://species.m.wikimedia.org/w/index.php?title=Template:MP_pictures&oldid=9072274
• Resize screen to 700px (or below).

What happens?:

Only one image per row. One column.

What should have happened instead?:

There should be as many images in a column as possible (within reason, so keeping a gap).

I've fixed this on the main page with CSS. See: https://species.m.wikimedia.org/wiki/Main_Page
It's a hack and not ideal because I had to force width: auto !important; which is not the same as keeping widths of images. See: https://species.wikimedia.org/w/index.php?title=Template:MP/styles.css&oldid=9072279#L-63

Software version (skip for WMF-hosted wikis like Wikipedia): wiki.

Other information (browser name/version, screenshots, etc.):

Current defaults:

Expected something more like this:

This rule seems to cause problems in Minerva:

@media all and (max-width: 720px) {
  .gallery .gallerybox {
    width: 100% !important;
  }
}

Not sure why this was added. I checked various types or galleries and it seems that without that all galleries look better. Maybe traditional gallery could be centered instead?