Quick CSS ignoring my code?

Hi there, I’m trying to apply border to the Publications section (link on private) using these codes:

.av-masonry-image-container img {
display: block;
margin: 0 auto;
border: 20px solid #E8E8E8;
}

or

.av-masonry-image-container {
text-align: center;
background-size: cover;
background-position: center center;
}

Wordpress (or something) is not recognizing my code. When I inspect element it doesn’t show the code I wrote.

On a side note, if i want these changes to happen on only one page is this code correct?:

.page-id-5829 .av-masonry-image-container { }

Thanks!