I want my lower divbox so that it docks with my upper one

my problem occurs from the smartphone breakpoint. Above this breakpoint everything is ok, respectively i don´t need it there.

For the Smartphone view (Either landscape and portrait) i want the page to scroll. For this i want that the lower divbox is docked to the upper divbox… So that the hight of the smartphone doesn´t affect the Slider and the background picture in it. Can anyone help me with that? Thank you for an answer!