After bug 1170782, we only use the typo metrics when the USE_TYPO_METRICS bit is explicitly set (http://www.microsoft.com/typography/otspec/os2.htm#fss). This is not the case in some old versions of math fonts, causing excessive line spacing. Users and packagers must upgrade to the latest version.
Latin Modern Math:
Debian: Fixed in testing (https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=799731)
Ubuntu: Fixed in Xenial Xerus (https://bugs.launchpad.net/ubuntu/+source/lmodern/+bug/1502701)
Fedora: Fixed in version 24
Created attachment 8666391 [details]
Math formula display issue
The square root sign is much too high in Firefox 43+ as you can see at
Also the denominator of the fraction is too high so maybe the problem lays in displacing fractions.
Are you able to tell which math font you use?
I suspect this is https://bugzilla.mozilla.org/show_bug.cgi?id=1170782 ; some old versions do not have the USE_TYPO_METRICS flag properly set.
I haven't set a font so it must be what Firefox (on Linux64) uses by default.
Created attachment 8666399 [details]
Default fonts are at https://dxr.mozilla.org/mozilla-central/source/modules/libpref/init/all.js#1929
What do you get with this testcase?
(You can also use the inspector on the <math> tag to check the font-family)
The font I used is Latin Modern Math.
Other fonts (at least some) display nicely, like for example DejaVu Sans.
The latest version (1.959) should not have the bug: http://www.gust.org.pl/projects/e-foundry/lm-math/download/index_html
Some Linux distros (e.g. Debian) still have an old version: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=799731
(In reply to Frédéric Wang (:fredw) from comment #5)
> Some Linux distros (e.g. Debian) still have an old version:
The bug just got closed in Debian sid today, so hopefully it will be the cases in other Debian-based distributions such as Ubuntu and Mint. Apparently, the latest build for Fedora 24 also have version 1.959 (http://koji.fedoraproject.org/koji/rpminfo?rpmID=6858749). I open an enhancement request in openSuse.
*** Bug 1211130 has been marked as a duplicate of this bug. ***
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*** Bug 1346633 has been marked as a duplicate of this bug. ***