Every frontend developer has inherited a CSS codebase where the color #2D5BE3 appears 47 times, where there are four different definitions of "spacing-medium" and none of them match, and where changing the primary button color requires a find-and-replace across twelve files that will inevitably miss two.
This is not a discipline problem. It is an architecture problem. And the solution is not more comments in the code or better naming conventions on their own. It is building a system that makes inconsistency structurally difficult.
This guide covers the practical implementation of CSS custom properties as a design token layer, naming conventions that survive team growth, and the component architecture patterns that hold up across real production projects.
What Design Tokens Actually Are (And What They Are Not)
Design tokens are the named values that represent the decisions of a design system: colors, spacing, typography scales, border radii, shadow levels. They are not the components themselves. They are the raw material that components are built from.
