Eight Columns layouts

Hi

I can’t figure out how to make an eight column layout with the layout fields, I tried

                layouts:
                  - "1/8, 1/8, 1/8, 1/8, 1/8, 1/8, 1/8, 1/8"

But it makes rows instead of columns, do you know why ?
Thx

See

The layout is based on 12 columns, so 8 is not possible.