changing post thumbnail problem

I've tried everything here and I don't see anyone on the forums with a similar problem... this seems like it should be so simple so I tried everything I could before asking.

I have a Newsroom page that lists all the posts. I tried changing the thumbnail image size with this:

@media only screen and (min-width: 980px){
.page-id-49 .size-auto, .size-full, .size-large, .size-medium, .size-thumbnail{
    max-width: 300px!important;
    height: 200px!important;
    object-fit: cover;
}
}

I had to add the !important or else it didn't work.

THE PROBLEM: The individual post pages now have the smaller sized images too. The page id doesn't seem to be targeting the thumbnails just on the page. I never had to target specific pages before but I found this:
https://generatepress.com/forums/topic/ccs-to-affect-only-one-page/

Am I doing something wrong here?
(links to pages below in private area)

Thanks!