How do I change the Red Line/Borders on my site?

I am creating a merch site for my brand and I purchased a template called “Merchify”.

I am getting the hang of editing the pages contents, but am having trouble with one thing.

As you can see in the Screenshot, there is a thin red line at the top of the page, and also a thin red line that is around the ‘Buy Merch’ button.

I cannot find the setting that is making that line red. I would like to change that color to black.

Would anybody know what I need to do in order to do this?


Here is my site Read-Only: LINK
(how to share your site Read-Only link)

Here is what the footer area looks like. As you can see, it also has that thin red line at the top. And if you look closely at the bottom sections CTA Button, it also has a red glow that animates when you hover over the button.

I would like to make that glow the green color that I use for my brand, and I would also like to change that line to Black.