Pin an element between the limits of a cotainer

[rene]

Hi everyone,
How can I add the effect, function of the Contact Form, of this site?
https://www.sellspot.mx/propiedades/centro-alpes/
Cant find it anywhere…
I just find the option of pin to screen, bot the whole screen… can’t configure any limit or parent to the header or footer…
Any ideas?
Thanks!

[andreas-kviby]

Feature Request