There is no downvote button on submissions only upvote and flag.
Should there be downvote buttons for submissions?
Maybe? I could go both ways. I think downvoting is important but it's also very easily abused. I like stackexchange's downvoting system where it comes at a cost.
It is, or was, 500 points.
The downvote on users only appeared for me as I pushed past about 650 I believe.