How to make two pictures overlap? _html/css_WEB-ITnose

It is required that two pictures overlap. The upper picture is a square implemented with CSS. I want its lower left corner to coincide with the lower left corner of the lower picture, and the side length is equal to the shorter side of the lower picture. How to achieve this? ?

Reply to the discussion (solution)

There is a z-index attribute in css

bingo, just use that z-index attribute