Questions regarding absolute position

[Dodra]

If you look at the site I am currently working on ( https://www.bronies.be/ )

You will most likely notice that the footer image on the left does have some issues.
This is what is not working: 

1. The footer should be the end, while now the body is still showing, due to the absolute image.
overflow-y hidden did not work here.

 

2. The bottom CSS code seems to be unable to understand -20%. How do i say that the absolute image should be 20% lowwer.


While I am on the subject: 
When i have an absolue element inside a relative element, how do i make the height of he relative element to fit in height to the absolue height.
Maybe this example will make my question clear: https://sunamena.be/forw3/index.php


Thanks in advance for the kind replies =D

Edited October 22, 2017 by Dodra