Whether the scroll position is still at the live caption edge.
With a bottom spacer of followPadPx, the pinned resting place has
distanceFromBottom ≈ followPadPx. Anything meaningfully above that means
the listener scrolled into older captions.
Parameters
distanceFromBottom: number
scrollHeight - scrollTop - clientHeight.
followPadPx: number
Height of the mid-viewport spacer below the live line.
slackPx: number = CAPTION_FOLLOW_NEAR_EDGE_SLACK_PX
Extra pixels allowed below the pad before unfollow.
Whether the scroll position is still at the live caption edge.
With a bottom spacer of
followPadPx, the pinned resting place hasdistanceFromBottom ≈ followPadPx. Anything meaningfully above that means the listener scrolled into older captions.