How to make perfect Google Forms header images

A few years ago, my friends and I created a just-for-fun ice cream business. (We made ice cream flavors inspired by our rescue dogs.) Making the ice cream aside, we wanted all other operations to be as low-effort as possible, so we used Google Forms to collect customer orders.  Google Forms definitely hit the no-fuss-yet-robust criteria, but its default color theme (purple) didn't match our style. So one silly dog photo and a few light edits later, we added a custom header image to Google F