There are many reasons you might wish to print a web page, and most of them don’t involve using all your printer ink to display an accurate representation of the page. More often than not the information is what’s important and that’s just fine.
If you do want to print an accurate copy of a website on the screen however, you need to enable a setting called Print Background (colours and images). Which can be found under the File > Page Setup on the Format & Options tab.
