Hi everyone. It seems to be a fairly popular issue, so I just wanted to quickly share how I stopped getting errors about my border sizes. I'm aware of setting browser zoom to 100% (ctrl+0). That did not resolve the issue for me. I'm using a Windows 10 laptop and changed my display settings value (right-click on desktop --> display settings): "Change the size of text, apps, and other items:" to 100%. It was previously 125% (the default, recommended setting), and once I changed it to 100% I was able to successfully complete all the exercises I was previously getting errors for (borders). Hope that helps some people.