Forum Bugs

Media query does not trigger when expected


I'm trying to convert the following HTML to PDF using the following command
prince a4.html -o ../prince.pdf --page-size A4

@page {
	size: A4;
	margin: 21mm;
	background: #fbfaf6;

.width {
	width: 200mm;
	background: silver;
	margin: 0 -21mm;
.shouldBeBlue {
	background: red;
@media (min-width: 200mm) {
	.shouldBeBlue {
		background: blue;
	<div class="width">width</div>
	<div class="shouldBeBlue">I'm not blue :-(</div>

But the "div.shouldBeBlue" stays red.

When I change the "min-width" in the media query to 171mm, the div does become blue.
Since an A4 sheet of paper is 210mm wide, I would expect this to be the case up until "min-width" is 210mm.

I have tried reducing the margins to 0, but this had no effect.

FWIW I first encountered this bug when attempting to match on a "min-width" of 700px, which should also still be hit on an A4 sheet of paper.
Prince is taking the page margins into account and measuring the page body area, you will need to reduce the page margins with --page-margin 0 on the command-line.