How to remove huge gap from layout on mobile?

[JanAbe]

I got a masonry layout which works fine on desktop but on mobile these huge gaps appear and I don't know how to fix it.

Here are some screenshots.

The first two pictures get placed correctly underneath each other:

But then this huge gap appears and I dont know why.

It might have something to do with my css styling?
Because when I remove my styling:

img {
  width: 100%;
}

the images get placed correctly underneath each other.

The problem then is that the images are too big.

Does someone know how to remove the huge gap?