I am using featured image in elements (header) for new website at https://jerryslimousineservice.ca. All looks great on desktop and tablet, but on mobile the image is much too large in both landscape and portrait.
you can set different mobile padding in the Header Element, which you can adjust to suit the mobile image. However the easiest thing is to use % padding, try around 28% top padding instead of 350px. It will then respond to the screen width.