For some reason our editor has become squashed which is being caused by .editor-styles-wrapper .wp-block with margin-left: auto; margin-right: auto; which adds 190px margin. The pages render correctly, and it looks ok in the customiser, just not when editing a page or post.
Just wondering if you had come across this before?
The content is Document => Container (gb-inside-container 1160px / 1200px wide with 20px margin either side) => Grid (760px ?) => Container => Headline