User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:63.0) Gecko/20100101 Firefox/63.0 Steps to reproduce: I connected to the IP of any local Sharp printer. Actual results: It has shrunk the tabs across the top so I can barely click on them, see screenshot 1. Expected results: See screenshot 2, this was captured from Microsoft Edge. In previous builds of Firefox it has worked fine. I believe it stopped working at build 62 or 63. May be further back however.

I can not view the screenshot because they are in a proprietary format. We need a public testcase as most people do not have that printer around for testing. Is it possible that you save the affected page and look if you can reproduce the problem with that saved page ?

(In reply to Matthias Versen [:Matti] from comment #1) > I can not view the screenshot because they are in a proprietary format. > > We need a public testcase as most people do not have that printer around for > testing. > Is it possible that you save the affected page and look if you can reproduce > the problem with that saved page ? Hi, Yes I can, I have managed to reproduce with the saved HTML file. I will attach along with the screenshots

You have to save it as "Web page complete" in the save dialog (filetype selection) because the pure html file still loads many resources from the printer. Please test if you can reproduce the issue with the saved file and then zip the html file including the folder with the additional files and attach it.

(In reply to Matthias Versen [:Matti] from comment #6) > You have to save it as "Web page complete" in the save dialog (filetype > selection) because the pure html file still loads many resources from the > printer. > Please test if you can reproduce the issue with the saved file and then zip > the html file including the folder with the additional files and attach it. I have attached the ZIP as requested. The issue still happens.

2:22.92 INFO: No more inbound revisions, bisection finished. 2:22.92 INFO: Last good revision: 5f50dd0905ec23b0d1fa1747905d5a1ef5f73dc2 2:22.92 INFO: First bad revision: 7d3fe27beec58d201a98d6bfcbe43d6e493348c6 2:22.92 INFO: Pushlog: https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=5f50dd0905ec23b0d1fa1747905d5a1ef5f73dc2&tochange=7d3fe27beec58d201a98d6bfcbe43d6e493348c6

csewell: For the time being, you can work around this by visiting the special URL "about:config", type "webkit" into the search field, and double-click on the entry for "layout.css.prefixes.device-pixel-ratio-webkit" to set that setting to false. Bug 1444139 was simply a pref-flip to toggle that setting to true. It make us honor this piece of "other.css" in the provided web content (roughly, this means "every screen that has pixels", i.e. this style is unconditionally applied): > @media screen and (-webkit-min-device-pixel-ratio:0) { > #tabMenuArea .tabMenu ul li { > height: 1px; > } >} They're styling this element with height:1px, which is bogus. If I remove that from their CSS, everything ends up fine. Chrome gets the same styling but it doesn't seem to honor this "height:1px" declaration. I'm not sure why.

This is fundamentally a table layout web-compatibility issue, relating to how percent heights are handled inside of small-specified-height table cells.

Our behavior on testcases 2 and 3 have been basically the same at least as far back as a Firefox 4.0 nightly from 2011-01-01 (probably a good deal further back than that, but builds from a year earlier won't run on my machine). So this isn't really a layout regression -- it's just that bug 1444139 got us newly opted in to some CSS that (in this case) happens to trigger a longstanding table layout incompatbility.