Setting Android Theme background color

I'm trying to modify the default background theme color, which should be easy but surprisingly I can't get it working. Please note that I want the change to be across the entire app, not just for a single activity. Here is my code:

styles.xml

<resources>

    <color name="white_opaque">#FFFFFFFF</color>
    <color name="pitch_black">#FF000000</color>

    <style name="AppTheme" parent="android:Theme.Light">
        <item name="android:background">@color/white_opaque</item>
        <item name="android:windowBackground">@color/white_opaque</item>
        <item name="android:colorBackground">@color/white_opaque</item>
    </style>

</resources>

and of course in the manifest

<application
    .
    .
    .
    android:theme="@style/AppTheme" > 
</application>

Android doc which I consulted on modifying themes: http://developer.android.com/guide/topics/ui/themes.html

I've tried switching between white_opaque and pitch_black for all the xml attributes but it doesn't change a thing. Any suggestions?

Okay turned out that I made a really silly mistake. The device I am using for testing is running Android 4.0.4, API level 15.

The styles.xml file that I was editing is in the default values folder. I edited the styles.xml in values-v14 folder and it works all fine now.

<resources>

    <!-- Base application theme. -->
    <style name="AppTheme" parent="android:Theme.Holo.NoActionBar">
        <item name="android:windowBackground">@android:color/black</item>
    </style>

</resources>

Open res -> values -> styles.xml and to your <style> add this line replacing with your image path <item name="android:windowBackground">@drawable/background</item>. Example:

<resources>

    <!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
        <!-- Customize your theme here. -->
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
        <item name="android:windowBackground">@drawable/background</item>
    </style>

</resources>

There is a <item name ="android:colorBackground">@color/black</item> also, that will affect not only your main window background but all the component in your app. Read about customize theme here.

If you want version specific styles:

> If a new version of Android adds theme attributes that you want to > use, you can add them to your theme while still being compatible with > old versions. All you need is another styles.xml file saved in a > values directory that includes the resource version qualifier. For > example: > > res/values/styles.xml # themes for all versions > res/values-v21/styles.xml # themes for API level 21+ only > > Because the styles in the values/styles.xml file are available for all > versions, your themes in values-v21/styles.xml can inherit them. As > such, you can avoid duplicating styles by beginning with a "base" > theme and then extending it in your version-specific styles.

Read more here(doc in theme).