tooltip: {
    formatter() {
        const x1 = Highcharts.dateFormat('%d/%m/%Y', this.x)
        const x2 = Highcharts.dateFormat('%d/%m/%Y', this.x2)
        const chantier = this.point.name
        const header = `<span style="font-size:10px">du ${x1} au ${x2}</span><table>`

        const body = `<tr>
    <td style="color:${this.series.color};padding:0">Chantier: </td>
    <td style="padding:0"><b>${chantier}</b></td>
  </tr>`

        const footer = '</table>'

        return header + body + footer
    },
    useHTML: true
}