This avoids the complex mutliply-nested blocks and makes the block style less reliant on a custom class. On mid-sized screens, we switch to plain horizontally-overlapping rectangles, and on small screens we stack the columns, and vertically-overlap.
register_block_style
This function is not in core WordPress yet, so we should check for it in case Gutenberg is deactivated.
This was forked from `pub/wporg-main` and `pub/wporg-plugins`, and then customized.