HighCharts organization diagram font size

Question

I can't set the font size on organization diagram, I want to be in 'em' unit because isn't looking good on mobile device.

I already tried:

Highcharts.chart('container', {
  chart: {
    height: 600,
    inverted: true
  },

  title: {
    text: 'Highcharts Org Chart'
  },

  dataLabels: {
    style: {
        fontSize: '30px'
    }
  },
  series: [{
    type: 'organization',
    name: '',
    keys: ['from', 'to'],
    data: [
        ['Shareholders', 'Board'],
        ['Board', 'CEO'],
        ['CEO', 'CTO'],
        ['CEO', 'CPO'],
        ['CEO', 'CSO'],
        ['CEO', 'CMO'],
        ['CEO', 'HR'],
        ['CTO', 'Product'],
        ['CTO', 'Web'],
        ['CSO', 'Sales'],
        ['CMO', 'Market']
    ],
    levels: [{
        level: 0
        dataLabels: {
        style: {
            fontSize: '30px'
        }
       }
        }],
    dataLabels: {
        style: {
            fontSize: '30px'
        }
    }
  }]
})

• Inside the serie
• In a level
• Globally

Any idea?

Anothers styles like "color" or "fontFamily" does work

Answer 1

The fontSize defined for each particular level or defined for the whole series works fine, even using em unit.

Demo: https://jsfiddle.net/BlackLabel/voz3btL1/

levels: [{
  level: 0,
  dataLabels: {
    style: {
      fontSize: '4em'
    }
  }
}],

API: https://api.highcharts.com/highcharts/series.organization.dataLabels.style.fontSize