CSS not having an effect on actual website


I’m new to WPMUDEV and am not quite sure if my question is properly directed to you.

I’ll ask it anyway. Here it is:

I have a wordpress site. I hired a web developer to make a theme. I liked it, but there were many aspects that I want to change. Instead of paying a new developer to change them, I wanted to change them myself.

So, I made a child theme. Put style.css and put custom.css and one template in the child theme.

I want to change aspects of the homepage. For instance, right now, the homepage has square boxes. And I want the boxes to have round edges. So, I want to make the border-radius 5px. When I do that in the Google chrome Inspector, it works! And it shows me that it works by changing the info on custom.css. But, when I change and update custom.css, nothing happens–the corners are not rounded.

I have tried to delete the browser history, in order to clear the cache. I read that this might fix the problem. But it doesn’t. I am wondering if you can help me figure out why the changes I try to make are not showing up. I am 99.9% sure the CSS changes are correct and they work fine in the Google Inspector mode.