User Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:41.0) Gecko/20100101 Firefox/41.0 Build ID: 20150917150946 Steps to reproduce: 1. Run Firefox 41.0 (and Nightly 44.0a1) on Ubuntu 14.04 (or 15.04) 2. Open http://ffmpeg.zeranoe.com/builds/rss.xml 3. Confirm font color and background color of #feedHeader Actual results: InfoBackground color is different in Firefox 41.0 and Nightly 44.0a1 on Ubuntu 14.04/15.04. #feedheader is hard to see because font color and background color are similar. Please check the following site in Firefox 41.0 and Nightly 44.0a1. Especially, InfoBackground is so different. http://webdesign.about.com/od/colorcharts/l/blsystemcolors.htm Expected results: CSS System Color should be same on a system.

Probably a regression from the GTK2 -> GTK3 switch.

inbound regression pushlog https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=d756733ac4c451b8ed7e0763350b1ce13ab10ba5&tochange=939320b957c588ad809e9b4a64b7f232dd4d9b72

Reporter, can you please try to set "browser.display.use_system_colors" to "false" in about:config? Looks like a bug that "browser.display.use_system_colors" does not have the effect we expect there.

(In reply to Martin Stránský from comment #3) > Reporter, can you please try to set "browser.display.use_system_colors" to > "false" in about:config? > > Looks like a bug that "browser.display.use_system_colors" does not have the > effect we expect there. "browser.display.use_system_colors" was already "false" as default. I have tried both of "true" and "false" but it was same result.

I see that, on Ubuntu 14.05, latest nightly (or at lease some 46.0 version). The tooltips itself (on UI) are OK but CSS HTML colors are wrong.

(In reply to magicp from comment #0) > InfoBackground color is different in Firefox 41.0 and Nightly 44.0a1 on > Ubuntu 14.04/15.04. #feedheader is hard to see because font color and > background color are similar. > > Please check the following site in Firefox 41.0 and Nightly 44.0a1. > Especially, InfoBackground is so different. > http://webdesign.about.com/od/colorcharts/l/blsystemcolors.htm The problem here is that InfoText is white and InfoBackground is transparent as per default Ubuntu gtk3 theme config. So it's a theme bug, when system colors are enabled.

btw, Fedora uses a semi-transparent color here: InfoBackground = 0xcc000000 but anyway I believe the real issue here is that "browser.display.use_system_colors" does not work while it's supposed to cover such theme bugs (IMHO).

Actually the pref which fixes this one is "ui.use_native_colors" set to false.