Button Styling - Read More vs Submit

Having some trouble getting the Read More and submit buttons to have similar colors. My read more looks fine. I'm using using Tom's Read More button snippet - https://docs.generatepress.com/article/activating-read-custom-excerpt/). I set the colors in the Customizer so that the background is black with white text. Upon hover, it reverses to a white background with black text.

The submit buttons used on the comment form and contact form, on the other hand, start correctly with a black background on white text. But upon hover, go completely white. I'd like the behavior to match the Read More button.

I'm testing this on a Digital Ocean droplet. I've cloned my prod site and set a hosts entry to map the clone's IP address to the URL boatbuildproject.com. When I go to the URL in my browser it then takes me to this test site instead. I've included the IP address in the website URL but without the hosts entry it will simply point to the root of NGINX.