No libraries, no server side. Just html. The page contains background image:
style="background: url('images/header_bg.png') center center; background-size: cover;"
When I save this page to PDF via Mozilla FireFox the quality of any background image is very poor (blurry), although images placed by <img> tags are OK. If I save an html page to PDF via MS Edge everything is OK with background images.
How to make good quality of background images when saving to PDF in FireFox?
It's a know bug without a solution yet.
https://bugzilla.mozilla.org/show_bug.cgi?id=1679514
There is a workaround of print the page enabling the background images instead of use save as pdf.
Steps to reproduce
Go to https://www.htmldog.com/examples/pullquotes2.html
Print preview the page.
Enable the "Print backgrounds" option.