Chrome 70 has just been released with an important change on how percentage row tracks and gutters work. You might need to update your site to avoid issues or breakages, more info at: https://blogs.igalia.com/mrego/2018/08/10/changes-on-css-grid-layout-in-percentages-and-indefinite-height/

See: https://developer.chrome.com/blog/new-in-chrome-70/?linkId=58284450