fix: scope css variables so that host css vars don't clash with excalidraw (#3199)

* fix: scope css variables so that host css vars don't clash with excalidraw

* update changelog

src/css/theme.scss

@@ -1,7 +1,7 @@
 @import "open-color/open-color.scss";
 @import "./variables.module.scss";
 
-:root {
+.excalidraw {
   --appearance-filter: none;
   --button-destructive-bg-color: #{$oc-red-1};
   --button-destructive-color: #{$oc-red-9};
@@ -34,9 +34,7 @@
   --shadow-island: 0 1px 5px #{transparentize($oc-black, 0.85)};
   --space-factor: 0.25rem;
   --text-primary-color: #{$oc-gray-8};
-}
 
-.excalidraw {
   &.Appearance_dark {
     background: $oc-black;
 

src/packages/excalidraw/CHANGELOG.md

@@ -12,6 +12,16 @@ The change should be grouped under one of the below section and must contain PR
 Please add the latest change on the top under the correct section.
 -->
 
+## Unreleased
+
+## Excalidraw API
+
+### Fixes
+
+- Scope css variables so that host css vars don't clash with excalidraw[#3199](https://github.com/excalidraw/excalidraw/pull/3199).
+
+---
+
 ## 0.4.2
 
 ## Excalidraw API