"Try getting the feet together. Do as you suggest. That is a verticl thigh over an angled shin."
Yes, that's the way it works. This puts the bent the knee forwards of the foot, and the body over the knee, which is to say also projected forward of the foot - but while maintaining vertical alignment.
"How can the bent knee be in front of the body. And the body verticlly aligned over the knee."
I didn't say the knee was in front of the body, I said the knee, and the body, are in front of the foot.
"Which means the knee is not in front of the body. Is it."
Which is why I didn't say it was - try READING next time.
Now of course there are situations where the knee would be ahead of the body, but those are different points in different actions, with entirely different characteristics.