ElementStacks

HTML

<script src="http://highcharts.com/js/testing.js"></script>
<div id="container" style="height: 400px"></div>

JavaScript

var data1 = [29.9, 71.5, 106.4, 129.2, 144.0, 176.0, 135.6, 148.5, 216.4, 194.1, 95.6, 54.4];
var data2 = [216.4, 194.1, 95.6, 54.4, 29.9, 71.5, 106.4, 129.2, 144.0, 176.0, 135.6, 148.5];
var categories = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul',
                                 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'];
var chart = new Highcharts.Chart({

    chart: {
        renderTo: 'container'
    },

    xAxis: {
        categories: categories
    },

    tooltip: {
        formatter: function() {
            var index = $.inArray(this.x, categories);
            var s = '<b>'+ this.x +'</b>';
            
            s += '<br/>'+ chart.series[0].name + ': ' + data1[index];
            s += '<br/>'+ chart.series[1].name + ': ' + data2[index];
            
            return s;
        },
        shared: false
    },

    series: [{ data: data1, visible: false },
             {data: data2}]
});