diff --git a/xwords4/android/app/src/main/res/values/styles.xml b/xwords4/android/app/src/main/res/values/styles.xml
index d99e7e7b7..48152edba 100644
--- a/xwords4/android/app/src/main/res/values/styles.xml
+++ b/xwords4/android/app/src/main/res/values/styles.xml
@@ -76,6 +76,7 @@
     <style name="expander_button">
         <item name="android:layout_width">32dp</item>
         <item name="android:layout_height">32dp</item>
+        <item name="android:background">@android:color/transparent</item>
         <item name="android:src">@drawable/expander_ic_maximized</item>
     </style>