How to Make a Lift/Drop Waterfall Chart with Regular Powerpoint Tables

I've seen elaborate waterfall charts that add and subtract financials in sequence but I've never made one myself.  A master deck from a client showed how.

Basically, it's a stacked bar chart where many of the bottom level bars are "white" or "transparent."   Add or subtract bars "float" above the transparent barstack below them.  Easy.

Below, the first bar is 340 and blue.  The next bar is a stacked bar with "340" in white or transparent, and then, a green bar for 30 floating on top of that.   To show a negative, for example, you'd have used instead a bar of 310 for the second bar and a red bar of 30 on top of it. 

click to enlarge

Note that these bars are slightly spaced (gap toothed) because they have a Format Data Series option of 20% gap width. 

I think the numbers floating on top are related to the "Format Data Labels" option but I'm not sure exactly how; I think by checking "Format Data Labels / Label Options / Label Contains / Value."

Note that the example has a truncated left axis (from 300 to 390).