Shadow depth depends on the direction and intensity of the light, as well as the distance of the object from the projection surface. The stronger the light, the sharper and darker the shadow; the weaker the light, the weaker the shadow.
There are too many examples of projection on the Internet.
LinkedIn adds an extremely subtle drop shadow at the bottom of the sidebar to create a sense of depth.
Google—perhaps the most difficult page to design on the Internet—still uses a subtle drop shadow on its search page.
To give an object a three-dimensional feel, you have many options besides simple projection. Long shadows can dramatically change the spatial relationships of objects on the page.
In the example below, after the same Coke can is given different shadows and dark parts, the entire spatial position appears completely different.
