How to make a CSS change on a specific post

Hello.

I’m trying to do a CSS change on specific a post at my page, and I’m not sure how to do that.

I can do that on a specific Page starting the command with “.page-id-xxx”, but it does not work for a Post page.
I trying doing the same starting the command with “.post-id-xxx”, but it did not work.
How can I do that?

For example, the command below worked for the page number 1241, how could I do the same for the post 1774?

.page-id-1241 .av-styling-no-styling .avia_image {
position: relative;
top: 19px;
}

Thanks