You should see teal underneath the dotted black border below.

There should be exactly four aqua rectangles visible inside the dotted border at all times.

As you scroll the element below the teal and aqua should not move.

However, as you scroll the aqua-and-teal element, a cat surrounded by an orange border with yellow dots should come into view, with its own associated nested scrolling mechanism.

As you scroll the aqua-and-teal element, the cat should move up and down with its border.

As you scroll the numbers inside the orange border, the cat should not move.

1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
10 11 12 13 14 15 16 17 18 19 20