pinch on list make the background-color of the list become dark(only happen in Android 4.0.3 native browser)

pinch on list make the background-color of the list become dark(only happen in Android 4.0.3 native browser)

When I pinch on list, the back ground-color of the list become dark.
Only Android 4.0.3 native browser cause this strange issue.
I confirmed this issue on "overview", "components", "API" list in :  http://jquerymobile.com/demos/1.2.0/

Please teach me how not to change color when I pinch.

Thanks.