How make transparent AppCompat style?

Question

My activity style must be from AppCompat theme.

So I make custom style and set activity style in manifest.

But black background is shown.

Below is custom theme

<style name="TransparentTheme" parent="@style/Theme.AppCompat">

    <item name="android:background">@null</item>
    <item name="background">@null</item>

    <item name="android:windowBackground">@null</item>
    <item name="android:colorBackgroundCacheHint">@null</item>
    <item name="android:windowContentOverlay">@null</item>
    <item name="android:windowIsTranslucent">true</item>
    <item name="android:windowAnimationStyle">@null</item>
</style>

Answer 1

use @android:color/transparent instead of @null

Answer 2

Use #99000000 in background instead of null