JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/c3/0.4.10/c3.min.css">
<script src="https://cdnjs.cloudflare.com/ajax/libs/c3/0.4.10/c3.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/2.1.4/jquery.min.js"></script>
<div id="chart"></div>

CSS

.c3-tooltip-container {
    background-color: #ccc;
    border: solid 1px black;
    padding: 20px;
}

JavaScript

var features = dates = defects = [
    1, 2, 3, 4, 5, 6, 7, 8, 9, 10
];


var chart = c3.generate({
    data: {
        columns: [
            ['data1', 30000, 20000, 10000, 40000, 15000, 250000],
            ['data2', 100, 200, 100, 40, 150, 250]
        ],
    },
    tooltip: {
        position: function () {
            var position = c3.chart.internal.fn.tooltipPosition.apply(this, arguments);
            position.top = 0;
            return position;
        },
        contents: function (data, defaultTitleFormat, defaultValueFormat, color) {
            var $$ = this, config = $$.config,
            titleFormat = config.tooltip_format_title || defaultTitleFormat,
            nameFormat = config.tooltip_format_name || function (name) { return name; },
            valueFormat = config.tooltip_format_value || defaultValueFormat,
            text, i, title, value;
            text = "<div id='tooltip' class='d3-tip'>";
            title = dates[data[0].index];
            text += "<span class='info'><b><u>Date</u></b></span><br>";
            text += "<span class='info'>" + title + "</span><br>";
            text += "<span class='info'><b><u>Features</u> : </b> " + features[data[0].index] + "</span><br>";
            text += "<span class='info'><b><u>Enhancements</u> : </b> " + defects[data[0].index] + "</span><br>";
            text += "</div>";
            return text;
        }
    }
});

var originalHideTooltip = chart.internal.hideTooltip
chart.internal.hideTooltip = function () {
    setTimeout(originalHideTooltip, 100)
};

$(".c3-tooltip-container")
    .css("pointer-events", "auto")
    .on('click', '.info:eq(2)', function () {
        alert($(this).text())
    })