.css to set every answer box with the same width

Good morning. My goal is to make the boxes in the image become the same size in width and height. Not being familiar with css I tried to search into this forum for other users who had the same problem but I did not find the perfect code and all the attempts made did not give the correct results or they give no results at all. Could someone give me a code to insert in the custom css of the look and feel page? Thanks so much for the support