I know this ain't the most visual stunning thing you came across lately. What's important about the animation is that it has a fixed rhythm, because it is intended to be a breathing trainer.
The idea is that you have to breath in for 4 seconds and then breath out for 6 seconds repeating this pattern for about 3 minutes and that 3 times a day.
If you do this your heart rhythm will become more balanced. This is called cardiac coherence and is known to reduce stress.
The webpage also works offline, if you added it to your homescreen (iPad/iPhone) or added it to your bookmarks.