Here is a Simple code to generate Box shadow. Use custom CSS option in Theme editor and create the box shadow bottom, left, right and or top. Just Change the values for your convenience to create suitable effects for your theme.
Below we gave a code with example of the Box image, Have a try and enjoy the design.
Box Shadow 1
box-shadow: 0 5px 10px rgba(154,160,185,0.05),
0 15px 40px rgba(166,173,201,0.2);
Box Shadow 2
box-shadow: 0 7px 30px -10px rgba(150,170,180,0.5);