Hi all! 

I've been trying to upload an image as background for our first game page.
I am struggling with getting the right sizing! I thought that as long as the width is correct, the height would not matter but here's the point: if I upload a 1920px wide image (to cover the whole screen, not just the column which I know being 960px wide), I can seem to be only able to update an image 1080 long, if I try something longer, I simply cannot upload it:

Am I simply missing something obvious?  Are there maximum sizes? (if so, which?)

Thanks!!