Image map a background image?

I am creating a website for an app I developed. The background of the website in an image that I photoshopped on a desk with an iPhone on it displaying the home screen of my app. I want to image map the background image so when you click on the screen it takes you somewhere. I am aware on how to image map so I already tested the image map using the tag. It works fine; however, I want the image to have the property “background-size: cover;” so it fills the screen at all times and maintains aspect ratio, leaving no whitespace. This property only works for background images or tags; unfortunately, you can only image map on tags (I think). I have been researching this for hours. Also, my image map is a polygon so it is unique. Thank you for any help in advance. enter image description here