A simpler navigation
We trimmed the top-level navigation. The "how-tos" section is gone. Its getting-started guide is now a top-level get started link, first in the navigation, and its writing guidance moved into foundations as content.
A clearer "What's new"
What's new is now two parallel sections: release notes and design notes.
Release notes is the log of what changed in each release. Design notes, like this one, explain the thinking behind notable changes. The pairing is the log and the story of the same work: one tells you what shipped, the other tells you why.
A new principle: content layering
We added content layering to our principles. It names something we already practiced but had not written down: showing what is useful for the task at hand rather than every option at once.
It is grounded in WCAG 3.0: Layout and Making Content Usable for People with Cognitive and Learning Disabilities, which both point to the same idea: respecting people's attention makes interfaces easier to understand and use.
Linkable section headings
Every section heading is now its own link. Hover a heading and a link icon appears, so you can grab a link straight to that section and share it or return to it later. This is a small piece of wayfinding: it helps people point each other to the exact spot they mean.
Try it out on the home page
The home page now has a small playground that shows a header, hero, some typography, and an accordion working together. You can edit the markup and watch the preview update live.
Reading about a pattern is one thing. Feeling a few of them work together, and being able to change them, is another. The playground is there to make the system approachable, not just documented.