support CSS Box Alignment properties on blocks
FWIW, this is important to do sooner rather than later, because the longer we wait, the greater the risk that Web compatibility will require that we not do this. However, it addresses some common developer requests like vertical centering, so it seems worth doing.
Reported: 4 years ago
¯\_(ツ_/¯
https://bugzilla.mozilla.org/show_bug.cgi?id=1105571