The challenge looks different (as if the challenge page has been refactored). It used to have a field to enter and submit a url. Now it does not and it appears as other challenges do where it tests it right there on the fcc website (on the challenge page).
The new Responsive Web Design curriculum content has been released.
Can I complete the old content?
Yes. The old content is still available, and has been moved to the bottom of the curriculum map and renamed to Responsive Web Design Legacy
What will happen to my progress?
Nothing. Your past progress will still be available in the Responsive Web Design Legacy curricula
Can I claim the old certificate?
The certifications are exactly the same. All you need to claim a certificate is to complete the 5 Certification Projects which are identical for both the Responsive Web Design and Responsive Web Design Legacy curricula
Should I stop doing the legacy content, and just start over with the new content?
This is entirely up to you. Majority of the topics are the same - just taught in a different way. (See Project-Based Curricula)
How do I use the new editor?
The new editor is as close to an external text editor as we wanted to get it. If the files for the challenge have been enabled, you can access the index.html and styles.css tabs which you should use for the respective code.
Two main differences between this editor and other online editors:
You need to link your styles.css file to your HTML (just like you would in real web-development), by adding the following line to the head of your HTML:
<link href="styles.css" />
You are encouraged to include the DOCTYPE, html, head and body tags for each project.
I’m not sure if that specific script for testing in codepen will still be available in the future.
Any new Responsive Web Design projects that you have not already submitted will need to be submitted through the freeCodeCamp editor. You can continue to work on your project using other platforms (including local development), but in order to submit a project you need to copy it over. If you have difficulty moving a project from CodePen (or elsewhere), people on the forum will try to help figure it out.
I suspect that there are not plans to remove the CDN testing link anytime soon, but it is possible that the tests may not be exactly the same.
When software changes, it can be a bit of a shock to our systems, but this is something that the team at freeCodeCamp has been working on for years and is very excited to finally release.