Hi
Style in Silverlight is similar to CSS of asp.net page. Silverlight style allows us to define a common set of formatting characteristics and apply them throughout our application to ensure the consistency in page design.
Here i have created style for button like this
<UserControl x:Class="SilverlightApplication3.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d" Height="300" Width="400">
<UserControl.Resources>
<Style x:Key="ButtonCSS" TargetType="Button">
<Setter Property="Foreground" Value="SeaGreen"/>
<Setter Property="FontSize" Value="28"/>
<Setter Property="Height" Value="50"/>
<Setter Property="Width" Value="200"/>
<Setter Property="FontStyle" Value="Italic"/>
</Style>
</UserControl.Resources><Grid>
<Button Content="Submit" Style="{StaticResource ButtonCSS}"/>
</Grid></UserControl>