java/res/color/gesture_floating_preview_color_you.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <!-- This is necessary to add alpha to dynamic colors to a single theme -->
    <item
        android:alpha=".9"
        android:color="@color/keyboard_background_you" />
</selector>