Rebuilding Firefox.com with Mozilla and Lincoln Loop on modern, native CSS with no preprocessors, and what that means for design systems today. Back in 2008, fresh out of college, I discovered CSS Zen Garden , Dave Shea’s project where one HTML file could be restyled into something completely different using nothing but CSS. It was a glimpse of the dream: clean, reusable design, fully separated from content. Then you tried to ship real client work, and the dream fell apart. There were no CSS variables. The properties available couldn’t express a full-fidelity design, so we leaned on server-side processing, images, table-based layouts, and endless hacks. Every browser rendered things differently, so much of the work was just making one design behave across all of them. Zen Garden showed what was possible in theory. Production was another story. That gap took the better part of two decades to close, and most of the closing happened in the last few years.…