Bug 206898

Created attachment 389041 [details] Issue first noticed in l.sans, which is subbed in for MONO = 0 styles (Also posted with additional screenshots at https://github.com/arrowtype/recursive/issues/307) ## Description of the problem In Safari on macOS & iOS, some glyphs keep a fixed advance width even if `letter-spacing` is changed significantly (up or down). This problem does not occur in Chrome or Firefox. This problem is not changed by any combination of variable axis values (e.g. by placing non-registered axes above their min value). Rather, it is present whenever a glyph has been substituted with `rvrn` (Required Variation Alternates, https://docs.microsoft.com/en-us/typography/opentype/spec/features_pt#tag-rvrn). Examples in Recursive font: - the lowercase `l` keeps same right margin in Sans & Mono styles (`MONO = 0 to 1`) - lowercase `f`, `g`, `i`, `r` have fixed advance width in Mono styles (`MONO = 1`) - Most lowercase glyphs have fixed advance width in slanted/Italic styles (`slnt < -7.49 or ital > 0.49`) ## To reproduce - Download variable version of Recursive, e.g. [Recursive v1.035](https://github.com/arrowtype/recursive/tree/7333e9d9d6fc68a4f12fd4a33b909bf05c43eb0b/fonts_1.035/Variable_TTF) - Drop into https://wakamaifondue.com using Safari web browser - Use test strings; try changing axis sliders to find various glyph substitutions ``` ala blb clc dld ele flf glg hlh ili jlj klk lll mlm nln olo plp qlq rlr sls tlt ulu vlv wlw xlx yly zlz ``` Useful long test string for italic styles: ``` aaa bab cac dad eae faf gag hah iai jaj kak lal mam nan oao pap qaq rar sas tat uau vav waw xax yay zaz aba bbb cbc dbd ebe fbf gbg hbh ibi jbj kbk lbl mbm nbn obo pbp qbq rbr sbs tbt ubu vbv wbw xbx yby zbz aca bcb ccc dcd ece fcf gcg hch ici jcj kck lcl mcm ncn oco pcp qcq rcr scs tct ucu vcv wcw xcx ycy zcz ada bdb cdc ddd ede fdf gdg hdh idi jdj kdk ldl mdm ndn odo pdp qdq rdr sds tdt udu vdv wdw xdx ydy zdz aea beb cec ded eee fef geg heh iei jej kek lel mem nen oeo pep qeq rer ses tet ueu vev wew xex yey zez afa bfb cfc dfd efe fff gfg hfh ifi jfj kfk lfl mfm nfn ofo pfp qfq rfr sfs tft ufu vfv wfw xfx yfy zfz aga bgb cgc dgd ege fgf ggg hgh igi jgj kgk lgl mgm ngn ogo pgp qgq rgr sgs tgt ugu vgv wgw xgx ygy zgz aha bhb chc dhd ehe fhf ghg hhh ihi jhj khk lhl mhm nhn oho php qhq rhr shs tht uhu vhv whw xhx yhy zhz aia bib cic did eie fif gig hih iii jij kik lil mim nin oio pip qiq rir sis tit uiu viv wiw xix yiy ziz aja bjb cjc djd eje fjf gjg hjh iji jjj kjk ljl mjm njn ojo pjp qjq rjr sjs tjt uju vjv wjw xjx yjy zjz aka bkb ckc dkd eke fkf gkg hkh iki jkj kkk lkl mkm nkn oko pkp qkq rkr sks tkt uku vkv wkw xkx yky zkz ala blb clc dld ele flf glg hlh ili jlj klk lll mlm nln olo plp qlq rlr sls tlt ulu vlv wlw xlx yly zlz ama bmb cmc dmd eme fmf gmg hmh imi jmj kmk lml mmm nmn omo pmp qmq rmr sms tmt umu vmv wmw xmx ymy zmz ana bnb cnc dnd ene fnf gng hnh ini jnj knk lnl mnm nnn ono pnp qnq rnr sns tnt unu vnv wnw xnx yny znz aoa bob coc dod eoe fof gog hoh ioi joj kok lol mom non ooo pop qoq ror sos tot uou vov wow xox yoy zoz apa bpb cpc dpd epe fpf gpg hph ipi jpj kpk lpl mpm npn opo ppp qpq rpr sps tpt upu vpv wpw xpx ypy zpz aqa bqb cqc dqd eqe fqf gqg hqh iqi jqj kqk lql mqm nqn oqo pqp qqq rqr sqs tqt uqu vqv wqw xqx yqy zqz ara brb crc drd ere frf grg hrh iri jrj krk lrl mrm nrn oro prp qrq rrr srs trt uru vrv wrw xrx yry zrz asa bsb csc dsd ese fsf gsg hsh isi jsj ksk lsl msm nsn oso psp qsq rsr sss tst usu vsv wsw xsx ysy zsz ata btb ctc dtd ete ftf gtg hth iti jtj ktk ltl mtm ntn oto ptp qtq rtr sts ttt utu vtv wtw xtx yty ztz aua bub cuc dud eue fuf gug huh iui juj kuk lul mum nun ouo pup quq rur sus tut uuu vuv wuw xux yuy zuz ava bvb cvc dvd eve fvf gvg hvh ivi jvj kvk lvl mvm nvn ovo pvp qvq rvr svs tvt uvu vvv wvw xvx yvy zvz awa bwb cwc dwd ewe fwf gwg hwh iwi jwj kwk lwl mwm nwn owo pwp qwq rwr sws twt uwu vwv www xwx ywy zwz axa bxb cxc dxd exe fxf gxg hxh ixi jxj kxk lxl mxm nxn oxo pxp qxq rxr sxs txt uxu vxv wxw xxx yxy zxz aya byb cyc dyd eye fyf gyg hyh iyi jyj kyk lyl mym nyn oyo pyp qyq ryr sys tyt uyu vyv wyw xyx yyy zyz aza bzb czc dzd eze fzf gzg hzh izi jzj kzk lzl mzm nzn ozo pzp qzq rzr szs tzt uzu vzv wzw xzx yzy zzz ``` ## Environment - Platform: macOS 10.15.2 (Catalina), iOS 13.2 - Font version: v1.030, v1.034, v1.035 ## Other details Issue spotted in live websites & reproduced at wakamaifondue.com and axis-praxis.org. Issue is not shown in static fonts, reinforcing the theory that this is a problem related to `rvrn`/GSUB. Also happens in other variable fonts, such as Fraunces (which uses `rvrn` to sub-in alternate versions of glyphs like n, s, m.