prefs: ["layout.flex.enabled:true",
        "layout.flex-flow.enabled:true",
        "layout.flex-direction.enabled:true",
        "layout.flex-wrap.enabled:true",
        "layout.flex-grow.enabled:true",
        "layout.flex-shrink.enabled:true",
        "layout.justify-content.enabled:true",
        "layout.align-items.enabled:true",
        "layout.align-self.enabled:true",
        "layout.align-content.enabled:true",
        "layout.columns.enabled:true",
        "layout.column-width.enabled:true",
        "layout.column-count.enabled:true",
        "layout.column-gap.enabled:true"]