Subgridunit variable
There seems to have been a discussion that was not conclusive about including a subGridUnit
variable in the themes.
This seems however, to already exist in the default theme's code (https://gitlab.coko.foundation/pubsweet/pubsweet/blob/master/packages/default-theme/src/index.js#L39).
Let's have a final discussion about this.
I think we should either standardize this or remove it from the themes.