[UWP][XAML]ColumnDefinitions Width=Star Not Working

Question

I have a Grid with the following ColumnDefinitions:

<Grid.ColumnDefinitions>
  <ColumnDefinition Width="*" MinWidth="360"/>
  <ColumnDefinition Width="*" MinWidth="360"/>
  <ColumnDefinition Width="*" MinWidth="360"/>
</Grid.ColumnDefinitions>

In this Grid, I have 2 Grids & a ScrollViewer. However, these 2 Grids & ScrollViewer do not have the same Width (not even the 2 Grids). Isn't Width="*" supposed to make them the same size? Am I misunderstanding what the * means? Do I need to do something else that I am forgetting? Thanks.

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Nathan Sokalski [e-mail] http://www.nathansokalski.com/