[Theme: Hemingway Rewritten] Header Image Displays Incorrectly on Desktops

For the header image, the theme recommends 1280×426 pixels. I made my custom header image those exact dimensions.

My image displays correctly on laptops but otherwise… desktops, tablets, and mobile, the header image displays wrong. Most of the text on the header image is hidden. Why after uploading an image with the dimensions that WP recommends is it still displaying wrong on these devices??