[system] Improve style function typings

mui · Sep 23, 2019 · 745639f · 745639f
1 parent 6a1c305
commit 745639f
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/packages/material-ui-system/src/index.d.ts b/packages/material-ui-system/src/index.d.ts
@@ -161,7 +161,7 @@ export interface StyleOptions<PropKey, Theme extends object> {
 }
 export function style<PropKey extends string, Theme extends object>(
   options: StyleOptions<PropKey, Theme>,
-): StyleFunction<{ [K in PropKey]: unknown } & { theme: Theme }>;
+): StyleFunction<{ [K in PropKey]?: unknown } & { theme: Theme }>;
 
 // typography.js
 export const fontFamily: SimpleStyleFunction<'fontFamily'>;