improved handling of placeholder hints
improved Python feedback
add tutorial/onboarding video
remove progress bar if no exercises (how code runs)
side nav: remove close button for C2 condition
onboarding video
improved sign-posting for navigation (unicode arrows)
improved handling of placeholder hints improved Python feedback add tutorial/onboarding video remove progress bar if no exercises (how code runs) side nav: remove close button for C2 condition onboarding video improved sign-posting for navigation (unicode arrows)