WordPress 5.0’s release in December 2018 made the new block-based editor (“Gutenberg”) the default experience for everyone. While Blocks have made it easier to add and display content, they introduce new sources of CSS for us to consider.
Crystabelle Lopez provided an overview of what blocks are, their associated CSS, and how to quickly figure out the source of problematic CSS on WordPress websites.
Note: click the gear icon and select Open speaker notes for a bunch of extra info and handy links!