Footer not on bottom

Hello!

So on one of my page-templates (single-article) there is this big featured-image in the header by default so I went ahead with display:none but the place which was occupied by it was still pushing my content down. But when I tried to move it up with absolute positioning, the footer wasn’t at the bottom anymore (you only see it with small window heights) which I guess has something to do with the header but I don’t completely understand it so far. I’d appreciate any help.

Here’s the code which made the footer go up:

.article-template-default .site-featured-image,.article-template-default .entry-header , .article-template-default .site-header.featured-image:after {
  display: none;
}

.site-featured-image,.article-template-default .entry-header , .article-template-default .site-header.featured-image:after {
	display: none;
}

.article-template-default .main-article{
  position: absolute;
  top: 10vh;
  left: 2%;
}

The page I need help with: [log in to see the link]