Building a design system a solo designer could actually maintain

BMG Money's mobile and web products had grown up separately, each with its own component library. The result was inconsistent UI across platforms, duplicated work every time something needed to change, and no single reference for designers, developers, or QA to check against.

As the only designer at the company, I built a single design system from the ground up — standardized, scalable, and accessible — meant to hold up across both platforms as the product grew, with documentation clear enough that developers and stakeholders could use it without asking me first.

Every color is a semantic token, not a hardcoded hex — and several shift value entirely between light and dark mode rather than just adjusting opacity, so contrast holds up in both themes.

Every text style in the product traces back to one of these named tokens — so "make the title a little bigger" becomes a token swap, not a guess.

Each of the 38 categories below follows an identical documentation pattern: what it is, when to use it, and a ready-to-copy reusable instance — so reading one page teaches you how to read all of them.

Rather than a single big-bang release, the system shipped in stages — each with its own scope and changelog entry, so progress stayed visible to stakeholders throughout.