Setting display:block; doesnt do anything

https://www.codecademy.com/paths/web-development/tracks/getting-more-advanced-with-design/modules/learn-responsive-design-module/lessons/sizing-elements/exercises/scaling-img-video

Hi,
I was in the middle of the exercise above, on the 4th step I change the display property value to ‘block’ but I can’t really understand why… it doesn’t seem like it changes something.
Furthermore, as far as I recall, the display property is inherited, so I tried to change the display property of the container to ‘block’, expecting to see both images in the footer each on its own line, but that also didn’t work.

any reason that’s the case? thanks!