Bottom/Top Gap between gallery images

Hello.

I tried several plugins for gallery and I’m having the same problem with all of them. There is a blank space at the bottom/top between every image.

The only css I’ve added is:

.blog-post {
margin-top: -50px;
}

.vision div.vision-border {
padding: 10px;
}

.blog {
padding-bottom: 0px !important;
}

Probably it’s a botched job but gives me the result I wanted and doesn’t affect the problem.

From my ignorance I guess it’s some parameter from the theme, but I couldn’t find out how to change it it. I would appreciate any help