score:2

Accepted answer

You are doing it wrong, chart2 is not an option. Change this :

$('#container2').highcharts({
    chart2: {
         backgroundColor:'Transparent',
         size:'100%'
    },
    ...
});

To this :

$('#container2').highcharts({
    chart: {
         backgroundColor:'Transparent',
         size:'100%'
    },
    ...
});

See the updated jsFiddle


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