Support uneven sized grid cells in hs.grid

Is there a away to define a 2x2 grid where the left side spans say 60% and the right side 40%? I'm not talking about adding more cells to the grid, but about resizing cell sizes on the fly to make windows snapped to the grid adjust automatically to the new layout. I'm often tiling windows horizontally, but I'm kind of stuck with a 50%-50% layout and not exactly keen on working with more cells and manually adjusting every single window to expand or shrink.

Hammerspoon is great, keep up the excellent work.