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 Windows 12 Concept.
macOS Users:
Select Code, then select Preferences, then select Theme, then choose Color Theme (or you can click on ⌘+K then ⌘+T).
Choose Windows 11 Concept.
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.