Page

To style a Page you can set the Style property.

<Page x:Class="MetroDemo.Navigation.InterestingPage"
 xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 Title="Interesting Page"
 Style="{DynamicResource MahApps.Styles.Page}">
 <StackPanel>
 <TextBlock>Sorry, nothing is here.</TextBlock>
 </StackPanel>
</Page>