I've been trying to get the infoboxes on my Wiki like this the whole day, but I just can't seem to figure it out how!

I really want to have this alternate background color design with no line separating the information and being able to assign colors to header, and I know it isn't just Wookieepedia that has this because the Stargate Fandom has it as well, but I just don't understand enough of everything I saw to make it happen. Can someone help me with this?