I wonder how to stop loading/disable grid-flexbox.css. I would like to use Bootstrap's media query breakpoint units in "px" instead of "em" used by grid-flexbox.css. I find it confused when I have both loading on the same site.
Besides, I wonder if this default grid-flexbox breakpoint originally adapting Bootstrap's breakpoint ? It seems Bootstrap changed to "em" once but now it's changed back again to "px" in v4. Perhaps it needs an update if so.