title: Overwrite Mahapps Metro style for me header Tabitem
body: <p>I am working with WPF and MVVM. I installed Mahapps Metro, this nuget package provides all styles for my app.</p>
  
  <p>I made a TabControl, but the FontSize that Mahapps uses for the header in each TabItem is very big for my application.</p>
  
  <p>I need to create a StaticResource that changes the FontSize of the header in a TabItem without removing others properties that Mahapps provides.</p>