With "scroll-snap-type: both mandatory", the scroller should always snap to
a visible element that has snap position defined on it.
With "scroll-snap-type: both proximity", the scroller can only snap to an
element if its snap position is close to the current position.
Scroll vertically and make sure the gray squares at right are not visible. Then the
gray squares shouldn't affect snapping to the blue squares.
With "scroll-snap-type: both mandatory", the scroller should always snap to
a visible element that has snap position defined on it.
This is written in the old-spec. Only Firefox supports it now.
This is written in the old-spec with proximity. Only Firefox supports it now.