microsoft / microsoft/monaco-editor

Editor is not adopting system theme settings:A11y_Monacoeditor_Theme

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@hawkticehurst is already working on this.

Since Apr 30, 2026.

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Description

Monaco Editor Playground Link

https://microsoft.github.io/monaco-editor/playground.html?source=v0.55.1#example-creating-the-editor-hello-world

GitHubTags:

#A11yTCS; #A11ySev3; #A11yMAS;#Desktopweb; #Win11; #Visual Studio Code Client; #VisualStudioCode-Web-Apr2021; #ChromiumEdge; #a11y-monacoeditor;#PartnerBug;#WCAG4.3.1; #SCIM:Bug4961959; #SCIM:Bug4961965; #SCIM:Bug4961983; #SCIM:Bug5126247; #SCIM:Bug59334165; #SCIM:Bug60928858;

Environment Details:

#URL: Monaco Editor (microsoft.github.io)
Application name: Monaco Editor
Chromium edge: Version 147.0.3912.86 (Official build) (64-bit)
Windows 11 Enterprise (Version 24H2)  
OS Build 26100.5074

Reproduction Steps
  1. Hit the URL: https://microsoft.github.io/monaco-editor/playground.html?source=v0.55.1#example-creating-the-editor-hello-world
  2. Monaco editor page will appear.
  3. Apply system themes
  4. Observe that editor is not adopting the system themea.
Actual Behavior

The editor does not follow the system (OS) theme. Even when the system theme is changed (e.g., Aquatic, Desert), the editor continues using its own previously selected theme.

Expected Behavior

The editor should adopt and reflect the system theme.

User Impact:

Users relying on system-level themes, especially High Contrast or Dark Mode for accessibility, may experience inconsistent visuals, reduced readability, and difficulty using the application effectively.

Attachment

https://github.com/user-attachments/assets/b771cdb1-f26d-4507-a675-e77f97ff5e2d

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  3. Fork the repository and make your change on a branch.
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Assessment

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