title: How make transparent AppCompat style?
body: <p>My activity style must be from AppCompat theme.</p>
  
  <p>So I make custom style and set activity style in manifest. </p>
  
  <p>But black background is shown.</p>
  
  <p>Below is custom theme</p>
  
  <pre><code>&lt;style name="TransparentTheme" parent="@style/Theme.AppCompat"&gt;
  
      &lt;item name="android:background"&gt;@null&lt;/item&gt;
      &lt;item name="background"&gt;@null&lt;/item&gt;
  
      &lt;item name="android:windowBackground"&gt;@null&lt;/item&gt;
      &lt;item name="android:colorBackgroundCacheHint"&gt;@null&lt;/item&gt;
      &lt;item name="android:windowContentOverlay"&gt;@null&lt;/item&gt;
      &lt;item name="android:windowIsTranslucent"&gt;true&lt;/item&gt;
      &lt;item name="android:windowAnimationStyle"&gt;@null&lt;/item&gt;
  &lt;/style&gt;
  </code></pre>