How to set a shadow fade effect?

To set the Fade effect of the shadow first get into the edit mode and click the pencil icon. Next click the style tab and choose the shadow icon. Then, choose which edges and click on the edges button. Next, choose the color from the drop down menu. Finally set the fade effect by sliding the slider or typing in the number of pixels you desire.

Fade is within the offset and is the amount or width of the color gradient from solid to white.

Step 3: Click on the edge symbol to enable (C) (At least one edge should be enabled). 

Step 4: Set the offset (E) and  fade (F) using the adjuster as per your requirement.

Note: Fade can be set between 1px-5px.