Setting activity background color of all screens

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XML

Mobile

Android

I'm trying to add a background color to all my app activities by declaring a theme but when I add a hex color code in the xaml declaration I get an error on the hex code.The code is as follows:

Create a themes.xml file in res/values:

<resources>
 <style name="MyTheme" parent="@android:style/Theme.Light"> 
  <item name="android:windowBackground">#FF0000</item>
 </style>
</resources>

... and then in your AndroidManifest.xml specify this as the theme for your activities to use.

<activity
        android:name=".MyActivity"
        android:theme="@style/MyTheme" />