They have it made on canvas. 3 background for the unit just a background made with a canvas that responds to mouse movement. There is certainly a way to do this in SVG, but there can be problems with the adaptability and maintaining adequate aspect ratio (even with special attributes viewBox and preserveAspectRatio can be torment).
I have a few demos with similar effect (in SVG):
- here is a simple drag effect, which just changes the one coordinate of the arch.
- here a more advanced example where I already yuzayu Cubic Bezier Curve, not the arch or quadratic Beziers.
My options for rAF bikes gspam this whole thing must be obviously easier.