This method tries to get the container to stretch to all 4 edges by setting the top, bottom, right, and left vales to 0.
Setting margin: auto on the container causes each opposite margin to be equal, centering the container in the parent
Note: This method assumes the height of the parent element and each child element is fixed and known. However, the number of child elements is unknown and the total height of child elements is dynamic.
Additional styles not related to the above have been used to make this demo more presentable.