How to change overlay opacity in Block Extended layout?

The opacity can be adjusted by adding the following CSS snippet to the Divi Theme Options Custom CSS area. Here 0,0,0 is the color code in RGB and .7 is opacity. Increase or decrease the opacity as required or use its own custom color instead of black (0,0,0). 

.et_pb_post_extra.el_dbe_block_extended.image-background .post-media:before { 2 background: rgba(0,0,0,.7); 3}