Mobile first using CSS grid layout

Hi everyone, thanks for looking into my solution. I tried to be very efficient, but if you have any input on how to make it more efficient, please let me know. My first thought was that I could build this without media queries, but in the end, there was one point where I would have two cards in the first row and on the second row I would have one card and an empty space. Is there a way to make the last card span the entire width automatically? Thanks in advance!