Look at the example below. The Border element has its style defined inline. I define a Style just for my Border elements based on its existing properties:

<Border Style="{StaticResource TitleBorder}">
Hi, I'm Mark Moeykens. I created this blog so I could post and reference my Windows Presentation Foundation info in one central location. Since I'm thinking I'm the only one that will be referencing this blog, I warn you to use the info at your own risk! Sorry, I might omit data if I already know it.
<Border Style="{StaticResource TitleBorder}">