✨(frontend) add default background to left panel for better a11y

defined a default background color to prevent issues with user stylesheets

Signed-off-by: Cyril <c.gromoff@gmail.com>

CHANGELOG.md

@@ -18,6 +18,7 @@ and this project adheres to
   - ♿ add pdf outline property to enable bookmarks display #1368
   - ♿ hide decorative icons from assistive tech with aria-hidden #1404
   - ♿ remove redundant aria-label to avoid over-accessibility #1420
+  - ♿ add default background to left panel for better accessibility #1423
 
 ### Fixed
 

src/frontend/apps/impress/src/features/left-panel/components/LeftPanel.tsx

@@ -43,6 +43,7 @@ export const LeftPanel = () => {
             min-width: 300px;
             overflow: hidden;
             border-right: 1px solid ${colorsTokens['greyscale-200']};
+            background-color: ${colorsTokens['greyscale-000']};
           `}
           className="--docs--left-panel-desktop"
         >