testimonials grid section

Hello everyone, Here is my last challenge using grid. Concerning resizing screen and arranging grid items, i tried to defined a larger grid to be able to redefine my items when my @media become smaller but it didn't work and i had each time to define a new grid then adjust items. (not sure that i'm clear ;-). By the way, is my method correct using the grid or is there a better approach ? Thanks in advance for your suggestions. Happy coding !