## Summary
Decision around CSS architecture for the shared library. Topic encompasses: CSS preprocessor (Less, Sass, CSS variables), conventions (BEM, utility classes, etc), design tokens, how styles should be exported, etc.
## Considerations
#### CSS preprocessor
* WVUI, other WMF team-specific libraries, and MediaWiki use Less, while WiKit uses Sass for reasons documented in [[ https://phabricator.wikimedia.org/T286951#7233145 | this comment ]].
* Note that CSS variables, a pure CSS option, are not supported in IE11.
#### Design tokens
See T266688 for details and previous discussion, including [[ https://phabricator.wikimedia.org/T266688#6884221 | WMDE's evaluation of using JSON-based tokens ]].
#### CSS Utility classes
See T285880 for previous discussion and more links.
#### Style scoping
See T258774 for details on how WMDE approached this for WiKit.
#### Relevant links
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## Decisions
#### Which CSS preprocessor will we use?
#### What design token architecture will we implement?
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