Interesting that they said: We use a standard 12-column grid for content (as to be evenly divisible by 2, 3 or 4), but we typically use the two outer columns as responsive gutters. We've found this to be the best approach for us since Webflow doesn't support the CSS calc function (which would allow us to mix pixel and VW units).
I wonder if this is outdated as Webflow does support CSS calc
