<!DOCTYPE HTML> <html> <head> <title>font-variant-position fallback</title> <meta charset="UTF-8"> <style> /* sups: 0-9 + - ( ) = subs: 0-9 + - ( ) */ @font-face { font-family: subsuper; src: url(../fonts/subsuper.woff); /* FiraSans with blank omega */ } body { margin: 20px; font-family: subsuper, sans-serif; } p { margin: 10px; font-size: 50px; line-height: 2; width: -moz-fit-content; background: black; } h4 { font-weight: normal; } span { font-size: 0.667em; } /* see NS_FONT_SUB_SUPER_SIZE_RATIO_LARGE */ </style> </head> <body> <h4>The black bars should NOT be the same length</h4> <p> XXXXXXXXXX </p> <p> X<span>XXXXXXXX</span>X </p> <p> X<span>XXXXXXXX</span>X </p> </body> </html>