These two properties are not standard at present, but a lot of time CSS authors want to be able to control the level and the vertical effect. Firefox 39 has supported. MDN: https://developer.mozilla.org/en-US/docs/Web/CSS/scroll-snap-type-x https://bugzilla.mozilla.org/show_bug.cgi?id=945584
scroll-snap-points-x and scroll-snap-points-y have been removed from the specification and I believe that support was removed from WebKit in https://trac.webkit.org/changeset/210024/webkit. I'm going to close this bug as invalid.