From df17b3bea838781737cd1ae223b2b47110a7e319 Mon Sep 17 00:00:00 2001
From: Prateek Kathal <prateekkathal@users.noreply.github.com>
Date: Wed, 20 Nov 2019 14:32:08 -0500
Subject: [PATCH] Theme-UI: Added useCustomProperties for old browsers support
 (#40529)

* Added useCustomProperties for old browsers support

* Added definition author

* Made useCustomProperties optional

* Removed trailing whitespaces
---
 types/theme-ui/index.d.ts | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/types/theme-ui/index.d.ts b/types/theme-ui/index.d.ts
index 588df7ce70..37b3557272 100644
--- a/types/theme-ui/index.d.ts
+++ b/types/theme-ui/index.d.ts
@@ -5,6 +5,7 @@
 //                 Brian Andrews <https://github.com/sbardian>
 //                 Rodrigo Pombo <https://github.com/pomber>
 //                 Justin Hall <https://github.com/wKovacs64>
+//                 Prateek Kathal <https://github.com/prateekkathal>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 3.1
 
@@ -76,6 +77,14 @@ export type ColorMode = {
 };
 
 export interface Theme extends StyledSystemTheme {
+    /**
+     * Enable/disable custom CSS properties/variables if lower browser
+     * support is required (for eg. IE 11).
+     *
+     * References: https://theme-ui.com/color-modes/#turn-off-custom-properties
+     */
+    useCustomProperties?: boolean;
+
     /**
      * Provide a value here to enable color modes
      */