Lessons on the website not to open; Java Script and responsive design lessons
Please try one of the following steps to move forward.
Force a refresh of your page with CTRL + F5.
or - Try the challenge in incognito or private mode.
or - Disable any/all extensions that interface with the freeCodeCamp website (such as Dark Mode, Ad Blockers, or Spellcheckers).
or - Ensure your browser is up-to-date or try a different browser.
I hope one of these will work for you.