Customizing Track Appearance
RadStepProgressBar allows you to customize the color and size of the track visual.
To change the color of the track's part that shows the progress, set the TrackFill property of RadStepProgressBar.
To change the thickness of the track, set the TrackThickness property of RadStepProgressBar.
<telerik:RadStepProgressBar TrackFill="#34A852" TrackThickness="30" SelectedIndex="1">
<telerik:RadStepProgressBarItem Content="Step 1" />
<telerik:RadStepProgressBarItem Content="Step 2" />
<telerik:RadStepProgressBarItem Content="Step 3" />
</telerik:RadStepProgressBar>