[1] Safari 7.0 (2015-11-04 23:06:29 +09:00 版) https://developer.apple.com/library/safari/releasenotes/General/WhatsNewInSafari/Articles/Safari_7_0.html#//apple_ref/doc/uid/TP40014305-CH5-SW9

Kerning and ligatures for text display are now enabled by default; you can disable them, if necessary, by setting text-rendering:optimizeSpeed.