>>> My Info: Win7_64, Nightly 49, 32bit, ID 20160526082509 STR_1: 0. Set DPI -> 125% : A) Set DPI level -> 125% in your OS [OR] B) Set layout.css.devPixelsPerPx -> 1.25 1. Look at one of separators listed below AR: Some of the separators look blurred (2px instead of 1px) because of bug 477157 ER: All separators should not look blurred Full list of separators in browser UI that look blurred because of bug477157 (explained in bug1162441) - terrible oneOffButtons "improvement" shoved into search bar and urlbar - separator between star and bookmarks button - customize mode: separators inside cut-copy-paste and zoom toolbarbuttons placed in Australis menu - tabs if developer edition theme is applied