<?xml version="1.0" encoding="utf-8"?>
<resources>
    <style name="LightTheme" parent="Theme.AppCompat.Light">
        <item name="android:actionButtonStyle">@style/NotificationNotesActionButtonStyle</item>
        <item name="preferenceTheme">@style/PreferenceThemeOverlay.v14.Material</item>
        <item name="android:navigationBarColor">?android:colorPrimary</item>
    </style>

    <style name="DarkTheme" parent="Theme.AppCompat">
        <item name="android:actionButtonStyle">@style/NotificationNotesActionButtonStyle</item>
        <item name="preferenceTheme">@style/PreferenceThemeOverlay.v14.Material</item>
        <item name="android:navigationBarColor">?android:colorPrimary</item>
    </style>

    <style name="NotificationNotesActionButtonStyle">
        <item name="android:textSize">14sp</item>
        <item name="android:textStyle">normal</item>
        <item name="android:minWidth">70dp</item>
    </style>
</resources>

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <style name="LightTheme" parent="Theme.AppCompat.Light">
        <item name="android:actionButtonStyle">@style/NotificationNotesActionButtonStyle</item>
        <item name="preferenceTheme">@style/PreferenceThemeOverlay.v14.Material</item>
    </style>

    <style name="DarkTheme" parent="Theme.AppCompat">
        <item name="android:actionButtonStyle">@style/NotificationNotesActionButtonStyle</item>
        <item name="preferenceTheme">@style/PreferenceThemeOverlay.v14.Material</item>
    </style>

    <style name="NotificationNotesActionButtonStyle">
        <item name="android:textSize">14sp</item>
        <item name="android:textStyle">normal</item>
        <item name="android:minWidth">70dp</item>
    </style>
</resources>

Revert setting navigation bar color
Revert setting navigation bar color

It was possible to end up with the same color for the navigation bar
background and buttons, making the buttons invisible.
