3 column preview card with CSS grid

I'm pretty happy with the result but i still have some questions over some difficulties i have:

• I used grid and made all three columns 1fr wide, was that the right choice ?
• As i shrink down the resolution for the mobile version, at 900px wide the content gest pushed out of the left side of the screen, how do i avoid that.
• in my mobile version, the content doesnt take the whole sceen (width) idk if i was supposed to do so but i would like it to be more responsive, i guess it has to do something with the "display: block;" I used since "grid-template-rows" didnt let me put the three cards in one long "strip". maybe flexbox would've been better ?

Thanks for your help.