What does "top down" mean? Is it an idiom?

Native speaker’s answer
Rebecca
So, yes and no! In this context, "top down" refers to the top cover of the car being left down, making the car get wet in the rain. It can also mean a direction of doing things- from the top to the bottom. There is another phrase "top-down", which refers to a system of government or management, where policies come from the highest positions in management to the employees working in the lower levels. Ex: The new regulations came from the top-down. Make sure you follow them. Ex: Place the toothpaste top down, so all of it goes to the opening. Ex: Why not fill the gap in the wall from the top down? Ex: They are old-fashioned with their top down management.