It is not for this specific plugin, but to demonstrate the full implementation possibilities. Each instance can be different. Implementers will likely have to play with the positioning of the start & end points to achieve the desired effect, e.g. lerp-end top:20% or bottom:75%. In our deployment of this feature we played with absolute positioning of the end element and eventually settled on top:5%. There will not always be an existing element to attach the lerp start or endpoint to.