To change drop shadow colour and transparency:
Double-click a shadow node to display the Shadow menu.

Make sure that the Shadow Active button is enabled.
To change the colour of the shadow, do one of the following:
To adjust the transparency of the drop shadow, use the Transparency field. When this field is set to 100, the shadow is completely transparent. When set to 0, the shadow is completely opaque.
Adjust the softness of a shadow using the softness fields. Use a value of 0.0 to have a distinct shadow. Increase the value to soften the shadow.
Use Shadow Mix to render shadows and surfaces according to their order in the Priority Editor, independently of their position in Z-space. This option makes it possible to have the shadow of one media on top of the shadow of another media. Shadow Mix is an option in the Z-Buffer box in the Rendering section of the Action Setup menu.
