With the site editor and block themes, the concept of Layout arrived. It took shape as a block support, which means it’s an add-on that provides a block with extra functionality. It’s also a fundamental part of how block themes work: Layout allows us to define the width of our post content, and arrange blocks horizontally or vertically, right or left aligned, inside container blocks. In terms of block styling, Layout is a complex feature because it affects child blocks in ways that go beyond CSS inheritance.
This talk goes into how far the Layout support has come since the site editor first made its appearance in 5.9, why it has been in experimental mode for so long, what you can do with it right now as a theme or block developer – and what you can expect of it in the future!