Why doesn't background-attachment work?

Question

css

Tell me why the background-attachment property does not work? (no background image) if we remove the upper block, then everything works fine, what is the reason for this and can it be done somehow to make it work for the lower block?
https://jsfiddle.net/0vywtx58/2/

Answer 1

Correct the size and set the position:

background-size: auto 100%;
background-position: top left;

https://webref.ru/css/background-size