Hello! If there is an easier way to do this, I couldn’t find it. But here is what I did:
1. Install and activate the plug-in called “CSS Theme Override”.
2. Access the plug-in through the “Settings” tab on the left side bar.
3. Enter the following code into the text box, replacing the hex code with whatever color you want:
.separator:after{ background-color: #37adba; }
4. Type “ALL” in the “Page or Post ID” tab.
Hope this helps!