Thank you @ArunDubey. Follow-up question: so I tweaked your CSS to make it work in the Custom CSS editor under Style. But I was wondering why one would want to put it anywhere else?
/* make the first option in all matrix questions square and gray*/ td:nth-child(2) .q-radio { -webkit-border-radius: 0% !important; border-radius: 0% !important; background-color: lightgray !important; }
Actually the provided CSS is for specific question. if you don’t have none option in any other matrix question then you can paste it directly into required question’s question text. but you want to do this in all question then you can paste under look and feel option like you already did.