Click on install again in the Visual Studio Code app.
Windows Users:
Select File, then select Preferences, then select Theme, then choose Color Theme (or you can click on Ctrl+K then Ctrl+T).
Choose either Windows 11 Light or Windows 11 Dark.
macOS Users:
Select Code, then select Preferences, then select Theme, then choose Color Theme (or you can click on ⌘+K then ⌘+T).
Choose either Windows 11 Light or Windows 11 Dark.
Recommendations
Visual Studio Code 1.0.0 or above
Although the extension should work on any version of Visual Studio Code, it hasn't been tested so it's recommended that you use a newer version of Visual Studio Code.