(change the product/component adequately if I missed something) This issue is part of a couple of tests, I'm doing comparing Firefox Android and Chrome Android for layout differences wrt viewport values. The tests are available at http://la-grange.net/2016/12/01/viewport/ Test 0003 - <name="viewport" content="width=device-width"> http://la-grange.net/2016/12/01/viewport/viewport-test-0003.html * Firefox sets the width of documentElement to the width of the device and let the image overflow. It is possible to scroll horizontally. * Chrome sets also the width of documentElement to the width of the device but shows the full image.

* Firefox test-0003-fx54.0a1.20170201-and4.4.4.png * Chrome test-0003-chr55.02883.91-and4.4.4.png

https://webcompat.com/issues/4481 * Because the content is not being resized to the viewport like Chrome does ( Bug 1336332 ) * we get the issue of not being able to scroll because of overflow ( Bug 1336346 ) <meta name="viewport" content="width=device-width"> html, body, nav { width: 748px !important; overflow-x: hidden !important; position: relative; }

Probably a variation of this issue. <meta name="viewport" content="width=device-width,initial-scale=1.0,maximum-scale=1.0,user-scalable=no"> The header is getting the right size, but the main content is constrained by .singular .entry-main { width: 100%; height: 100%; -webkit-box-flex: 1; -webkit-flex: 1 1 820px; -ms-flex: 1 1 820px; flex: 1 1 820px; -webkit-align-self: flex-start; -ms-flex-item-align: start; align-self: flex-start; } which makes it jump out of the window on Firefox. While on Chrome Android the content is being resized to fit the viewport. We can fix it with `flex: 1 1 auto;` instead of `flex: 1 1 820px;`

comment 3 is really closer to bug 1331692 (which is part of bug 1136312), as I've now noted on https://webcompat.com/issues/4746