Stick footer to bottom when page content is less


Hi there,
I come to you today to report a minor CSS bug (to be checked if it does the same for you):
When I load a page and the content is shorter than the size of the screen, the footer does not go to the very bottom of the screen, it is placed correctly only if, afterwards, I resize my window.
I made a short screenshot for you to make it clearer:
Thank you for your help!
Warm regards,