master
[material-ui] Return styles directly if the selector is `&` when using `applyStyles` (#43633)
[code-infra] Enable undefined addition to optional properties (#47750)
[material-ui][Grid v1] Fix regression spacing prop with string value (#44376)
[system] Add `spacing` theme token to be used in `theme.spacing()` (#40224)
[internal] perf: sx (#44254)
[code-infra] Vitest test migration (#44325)
[system] Add `applyStyles()` to theme (#40667)
[system] Make `createBreakpoints` independent for stringify theme (#43048)
[code-infra] Convert leaf @mui/system .js+.d.ts pairs to TypeScript (part 1) (#48578)