Created attachment 8872936 [details] full-half-pre.htm User Agent: Mozilla/5.0 (X11; Fedora; Linux x86_64; rv:53.0) Gecko/20100101 Firefox/53.0 Build ID: 20170517123028 Steps to reproduce: Use fullwidth and halfwidth form of latin characters in the same <pre> element. An example is attached, or can be seen by navigating to the following page: https://jsbin.com/tezizasomo Stackoverflow user 'snailplane' also reproduced this bug/antifeature here: https://japanese.meta.stackexchange.com/questions/1023/preformatted-text-in-japanese-doesnt-line-up-properly/ Actual results: Fullwidth forms are a few pixels too narrow, therefore misaligning the characters from the grid. Expected results: The fullwidth forms should be twice the width of the halfwidth forms, therefore aligning to the grid.
I forgot to mention, this is not a Firefox specific issue. I have also reproduced this in Chrome 58 (Fedora 25), as well as IE11 and Edge on a friend's Win10 computer. This is the Blink engine bug report: https://bugs.chromium.org/p/chromium/issues/detail?id=728142