display property values, originally intended for Mozilla application UI, are no longer available from web content. The standard Flexible Box Layout or Grid Layout should be used instead.
For the meantime, the following values will be left due to concerns over compatibility issues. Firefox developers are planning to use Telemetry to understand the usage on the web before removing these exceptions.
-moz-inline-box are also deprecated as of Firefox 63.
-moz-inline-box have been removed with Firefox 64.