However, it is not good, because it always ignore time.
If we write "delay: 0.5s" but it delays 0.2 or 0.8 or 0.9 or ... and so on.
Yes, delay is unreliable!
So, we must set delay 0 and shift keyframes.
But, it is troublesome so I create command line tool.
It needs Python3.x
How to use
Write CSS animation input.txt
It creates export output.txt
And, you replace your animation to them.
If you don't know how to use it I will tell you.