NavigationView Pane background

One of the possible options to customize your UI is to override the following two theme resources: NavigationViewDefaultPaneBackground and NavigationViewExpandedPaneBackground.

You would generally modify these two resources to customize the appearance of the Acrylic Brush, by overriding them the following way:

<AcrylicBrush x:Key="NavigationViewDefaultPaneBackground"
              BackgroundSource="Backdrop" TintColor="Blue" TintOpacity=".6"/>

I would figure it is possible to simply define aSolidColorBrush instead of an AcrylicBrush, therefore changing the Acrylic background to a solid color, and removing entirely the acrylic from the NavigationView Pane.

<SolidColorBrush x:Key="NavigationViewExpandedPaneBackground" Color="Red"/>
<SolidColorBrush x:Key="NavigationViewDefaultPaneBackground" Color="Red" />