Add this type of shodow

Hellow, this is my first post,

Im a begginer with css, i can edit themes add and remove atributes, so.. i know one way or two to add shadows around objects, but i find imposibile to add the shadow like in the picture.

Is there a way to make this shadow only with css,without the help of png images, the shadow its spread only on the bottom-left and right.

Sorry for the english.