Bug#818061: iceweasel: Form elements such as input and select have huge font on hidpi screen

[Andy Smith]

Package: iceweasel
Version: 44.0.2-1
Severity: normal

Dear Maintainer,

I've just installed testing and Iceweasel on a laptop with a fairly high
resolution display; 2560x1440. To make Iceweasel usable I needed to set
layout.css.devPixelsPerPixel to 1.5 otherwise everything was very tiny.
However, this leaves just form elements like <option>, <input> and
<textarea> using a really big font size.

If you look at this JSFiddle:

    https://jsfiddle.net/xwfjvpup/2/

It renders like this for me:

    http://imgur.com/1Kw6XmO

Form elements that have font styling on them appear correctly, but
those with only styling on a parent seem to use -moz-system-font which
in my case is coming out as 28.45px.

My system font is Cantarell Regular 16. I don't know if that multiplied
by 1.5 would result in 28.45px font, but in any case the rest of Firefox
(UI and content) is okay, and reducing my system font size makes the
rest of the system appear unusably small.

If I could work out a way to override -moz-system-font then that would
probably be an acceptable workaround, but I cannot find a way.

This issue persists without any extensions and also with upstream
Firefox.

I also tried:

- Changing font preferences in Preferences > Content > Advanced. DOM
  Inspector says that -moz-system-font is selected no matter what is in
  use here.

- Overriding in userChrome.css. This is only for UI, so doesn't affect
  content, and does nothing for me.

- Overriding in userContent.css. This works, but I am unsure of the
  precedence between userContent.css and page CSS, so I worry about
  overriding styles that author has specifically put on form elements.

So as it is, I am overriding in userContent.css because sites I need to
use are unusable otherwise, e.g. form elements expand over the top of
nearby links, leaving me unable to click on them.


-- Package-specific info:

-- Extensions information
Name: Default theme
Location: /usr/lib/iceweasel/browser/extensions/{972ce4c6-7e08-4474-a285-3208198ce6fd}
Package: iceweasel
Status: enabled


-- Plugins information
Name: Gnome Shell Integration
Location: /usr/lib/mozilla/plugins/libgnome-shell-browser-plugin.so
Package: gnome-shell
Status: enabled

Name: iTunes Application Detector
Location: /usr/lib/mozilla/plugins/librhythmbox-itms-detection-plugin.so
Package: rhythmbox-plugins
Status: enabled


-- Addons package information
ii  gnome-shell    3.18.1-1     amd64        graphical shell for the GNOME des
ii  iceweasel      44.0.2-1     amd64        Web browser based on Firefox
ii  iceweasel-l10n 1:44.0.2-1   all          English (United Kingdom) language
ii  rhythmbox-plug 3.3-1        amd64        plugins for rhythmbox music playe

-- System Information:
Debian Release: stretch/sid
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: amd64 (x86_64)

Kernel: Linux 4.3.0-1-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages iceweasel depends on:
ii  debianutils               4.7
ii  fontconfig                2.11.0-6.3
ii  libasound2                1.1.0-1
ii  libatk1.0-0               2.18.0-1
ii  libc6                     2.21-9
ii  libcairo2                 1.14.6-1
ii  libdbus-1-3               1.10.6-1
ii  libdbus-glib-1-2          0.106-1
ii  libevent-2.0-5            2.0.21-stable-2+b1
ii  libffi6                   3.2.1-4
ii  libfontconfig1            2.11.0-6.3
ii  libfreetype6              2.6.3-3
ii  libgcc1                   1:5.3.1-10
ii  libgdk-pixbuf2.0-0        2.32.3-1.2
ii  libglib2.0-0              2.46.2-3
ii  libgtk2.0-0               2.24.29-1
ii  libhunspell-1.3-0         1.3.3-3+b2
ii  libnspr4                  2:4.11-1
ii  libnss3                   2:3.21-1.1
ii  libpango-1.0-0            1.38.1-1
ii  libsqlite3-0              3.10.2-1
ii  libstartup-notification0  0.12-4
ii  libstdc++6                5.3.1-10
ii  libvpx3                   1.5.0-2
ii  libx11-6                  2:1.6.3-1
ii  libxcomposite1            1:0.4.4-1
ii  libxdamage1               1:1.1.4-2+b1
ii  libxext6                  2:1.3.3-1
ii  libxfixes3                1:5.0.1-2+b2
ii  libxrender1               1:0.9.9-2
ii  libxt6                    1:1.1.5-1
ii  procps                    2:3.3.11-3
ii  zlib1g                    1:1.2.8.dfsg-2+b1

Versions of packages iceweasel recommends:
ii  gstreamer1.0-libav         1.6.3-1
ii  gstreamer1.0-plugins-good  1.6.3-1

Versions of packages iceweasel suggests:
pn  fonts-lmodern          <none>
pn  fonts-stix | otf-stix  <none>
ii  libcanberra0           0.30-2.1
ii  libgnomeui-0           2.24.5-3.1
ii  libgssapi-krb5-2       1.13.2+dfsg-5
pn  mozplugger             <none>

-- no debconf information