Child-proof paper or cardboard container

A paper or cardboard container, comprising:

• a container body comprising a bottom wall, a front wall, a rear wall, and two side walls, wherein the front wall, the rear wall and the side walls have respective upper edges defining an opening opposite the bottom wall, wherein each of said side walls comprises an outer layer having a through hole, and an inner layer having a through window facing the through hole of the outer layer,
• a lid movable between an open configuration and a closed configuration, wherein the lid comprises a top wall and a pair of sides, wherein each of said sides has an engagement tab folded onto a respective outer surface, wherein in said closed configuration the respective outer surfaces of said sides are in contact with respective portions of inner surfaces of respective side walls of the container body, and wherein in said closed configuration the engagement tabs of said sides of the lid engage respective through windows of said side walls of the container body and keep the lid closed on the container body,
• wherein at least one of said side walls comprises:
• an intermediate layer disposed between said inner layer and said outer layer and having a through opening facing said through hole of said outer layer, and
• a slider movable in said through opening of said intermediate layer and guided between said inner layer and said outer layer, wherein said slider is movable between a locking position where the slider faces said through hole of said outer layer and prevents a user from accessing the respective engagement tab, and an unlocking position where the slider is moved away from said through hole of said outer layer and allows the user to disengage the respective engagement tab by inserting a finger into the respective through hole and pressing inward on the respective engagement tab.