Adding a background image to a passage + making images responsive

Hello,

So this is a two parter for Harlowe:

1. How do I add an image into a passage and have it appear as the background and be responsive to the size of the screen (so it fills the screen no matter how big or small it gets - without distorting the dimensions though.)

2. How do I add a regular image into a passage and make it responsive like the text?

Thanks!