You forgot to close your first two color-stop and have an extra closing brace at the very end. Also, I would suggest using adding the regular linear-gradient if you want the background to show for browsers that do not support either vendor prefix.

Edit:

Also, I am pretty sure the "#RIGHT_SKYSCRAPER" id isn't used anymore so that whole second part can probably be removed. Or perhaps it is part of some feature/script I don't know about?

Thank you! Such a simple mistake. I feel like I'm learning this all over again.