When I try your first method it looks like this... https://i.imgur.com/vf3Fiqj.png then the cad becomes like this https://i.imgur.com/9PJ48u0.png
I think maybe I put in the mx style code wrong way how is the right way?
You added an extra key on the bottom row instead.
This raw code works for the basic ANSI layout:
[{a:7},"","","","","","","","","","","","","",{w:2},""],
[{w:1.5},"","","","","","","","","","","","","",{w:1.5},""],
[{w:1.75},"","","","","","","","","","","","",{w:2.25},""],
[{w:2.25},"","","","","","","","","","","",{w:2.75},""],
[{w:1.25},"",{w:1.25},"",{w:1.25},"",{_s:2,w:6.25},"",{w:1.25},"",{w:1.25},"",{w:1.25},"",{w:1.25},""]
The relevant part modifying the spacebar part being {_s:2,w:6.25}