CSS Issue – trying to customize Genesis child theme, my edits not being applied

Hi everyone, and thanks for reading.

1 – I’m new to WordPress, I used to make websites over a decade ago so I’m familiar with coding HTML and CSS but have been out of the game for a long time.

2 – I’ve searched a lot both in WP forum, codex, and other sites, and am where I can’t figure it out by myself.

Working on a website, WP-self hosted, Genesis framework, Enterprise Pro Theme by StudioPress, with a child theme customized for us by a pro developer, I’m doing content updates and trying to refresh the look / feel of the site.

I’m trying to style a UL of PDF’s. What I am trying to acheive is each LI is its own bordered box, within that box being a JPG thumbnail of the PDF with title to the right, with text vertically centered.

When I create a test page outside of WP, the list styles roughly the way I want it to, I need to polish a little bit but it has the big elements I want.

When I paste that exact CSS into the theme editor in WP dashboard, and edit my page, the CSS doesn’t apply, it doesn’t even seem to get called. When I paste that CSS directly into the page, using style tags, directly in the WP page editor, it seems to work.

Can’t figure out where I’m screwing up, is it the way I’m selecting the UL / LI’s, is it that some other style sheet is overriding my edits, or am I screwed up in some other way?

What I get when I paste the style directly into the page content:
https://e3a.30f.myftpupload.com/testing-format-good/

What I get when I leave the styling in the site main style sheet:
https://e3a.30f.myftpupload.com/testing-format-not-working/

The colors are just there to help me visualize what DIVs are containing what, etc.