I found out host names on "Trigger overview" screen in few browsers are not rotated (and shown horizontally instead of vertically), please see screenshots attached.
List of affected browsers and systems:

OSX 10.11.3 Firefox 44 - affected
Ubuntu 14.04 Firefox 44 - affected
Window 7 Firefox 44 - affected
Window XP Firefox 44 - affected
OSX 10.11.2 Chrome 48 - affected
Ubuntu 14.04 Chrome 48 - affected
Window 7 Opera 35 - affected
Ubuntu 12.04.5 Firefox 42 - not affected
Ubuntu 12.04.5 Chromium 43 - not affected
Debian 8 stable Iceweasel 38 - not affected
OSX 10.11.3 Safari 9 - not affected
Android 4.2.2 Yandex browser - not affected

Here is part of the code which adds rotating css for these browsers:

?  zabbix-2.4.7  egrep '!IE9' ./frontends/php/include/classes/html/CTableInfo.php -A 4
					if (!IE9) {
						jQuery(".vertical_rotation_inner", table).css({
							"writing-mode": "tb-rl"
						});
					}