How can I create a pyramid grid layout?

I’m guessing this is fairly simple, but I have three elements that I’d like to place in a grid. Typically I’d just put the three elements on the same row, but the size of the elements makes it necessary to have two elements on top and one below them, centered. Is there a way to do this?

You can drag the bottom div to take up both bottom grid boxes, then center align the elements within this div with flex.