How can I force browsers to print background images in CSS?

With Chrome and Safari you can add the CSS style -webkit-print-color-adjust: exact; to the element to force print the background color and/or image

Browsers, by default, have their option to print background-colors and images turned off. You can add some lines in CSS to bypass this. Just add:

* {
    -webkit-print-color-adjust: exact !important;   /* Chrome, Safari 6 – 15.3, Edge */
    color-adjust: exact !important;                 /* Firefox 48 – 96 */
    print-color-adjust: exact !important;           /* Firefox 97+, Safari 15.4+ */
}