I had another question. I understand that I can style individual posts (and post excerpts) by category using CSS.
But from what I’ve read (here: https://codex.wordpress.org/Function_Reference/post_class), the following snippet of code needs to be included somewhere in the theme files: <?php post_class(); ?>.
After this is added, I can then style the CSS according to whatever classes might apply, including by category.
I am currently using the blog masonry layout. Can you tell me where I would add this snippet?