JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/c3/0.4.10/c3.min.js"></script>

<body>
  <br><br>
  <div id="c3_chart" style="width: 90%; height: 270px"></div>

CSS

.c3 svg {
  font: 10px sans-serif
}

.c3 line,
.c3 path {
  fill: none;
  stroke: #000;
}

/* In this example I changed the line color to red for c3_chart_2 */
#c3_chart_2.c3 line,
#c3_chart_2.c3 path {
  fill: none;
  stroke: red;
}

.c3 text {
  -webkit-user-select: none;
  -moz-user-select: none;
  user-select: none
}

.c3-bars path,
.c3-event-rect,
.c3-legend-item-tile,
.c3-xgrid-focus,
.c3-ygrid {
  shape-rendering: crispEdges
}

.c3-chart-arc path {
  stroke: #fff
}

.c3-chart-arc text {
  fill: #fff;
  font-size: 13px
}

.c3-grid line {
  stroke: #aaa
}

.c3-grid text {
  fill: #aaa
}

.c3-xgrid,
.c3-ygrid {
  stroke-dasharray: 3 3
}

.c3-text.c3-empty {
  fill: gray;
  font-size: 2em
}

.c3-line {
  stroke-width: 1px
}

.c3-circle._expanded_ {
  stroke-width: 1px;
  stroke: #fff
}

.c3-selected-circle {
  fill: #fff;
  stroke-width: 2px
}

.c3-bar {
  stroke-width: 0
}

.c3-bar._expanded_ {
  fill-opacity: .75
}

.c3-target.c3-focused {
  opacity: 1
}

.c3-target.c3-focused path.c3-line,
.c3-target.c3-focused path.c3-step {
  stroke-width: 2px
}

.c3-target.c3-defocused {
  opacity: .3!important
}

.c3-region {
  fill: #4682b4;
  fill-opacity: .1
}

.c3-brush .extent {
  fill-opacity: .1
}

.c3-legend-item {
  font-size: 12px
}

.c3-legend-item-hidden {
  opacity: .15
}

.c3-legend-background {
  opacity: .75;
  fill: #fff;
  stroke: #d3d3d3;
  stroke-width: 1
}

.c3-tooltip-container {
  z-index: 10
}

.c3-tooltip {
  border-collapse: collapse;
  border-spacing: 0;
  background-color: #fff;
  empty-cells: show;
  -webkit-box-shadow: 7px 7px 12px -9px #777;
  -moz-box-shadow: 7px 7px 12px -9px #777;
  box-shadow: 7px 7px 12px -9px #777;
  opacity: .9
}

.c3-tooltip tr {
  border: 1px solid #CCC
}

.c3-tooltip th {
  background-color: #aaa;
  font-size: 14px;
  padding: 2px 5px;
  text-align: left;
  color: #FFF
}

.c3-tooltip td {
  font-size: 13px;
  padding: 3px 6px;
  background-color: #fff;
  border-left: 1px dotted #999
}

.c3-tooltip td>span {
 ...

JavaScript

const TICK_WIDTH = 35;
var chart = document.getElementById("c3_chart");
var visibilityThreshold = chart.clientWidth / TICK_WIDTH;
function addLabelToTicks() {
    var allTicks = document.querySelectorAll("#c3_chart .c3-axis-x.c3-axis > g");
    var visibleTicks = Array.from(allTicks)
        .filter(tick => !tick.querySelector("line[x1='0'][x2='0'][y2='0']"));
    if (visibleTicks.length < visibilityThreshold) {
        visibleTicks.forEach(tick => tick.querySelector("text").style.display = "block");
    }
}

var chart = c3.generate({
    bindto: '#c3_chart',
    data: {
        x: 'x',
        //        xFormat: '%Y%m%d', // 'xFormat' can be used as custom format of 'x'
        columns: [
            ['x', '2013-01-01', '2013-01-02', '2013-01-03', '2013-01-04', '2013-01-05', '2013-01-06',
                '2013-01-07', '2013-01-08', '2013-01-09', '2013-01-10', '2013-01-11', '2013-01-12', '2013-01-13', '2013-01-14', '2013-01-15', '2013-01-16', '2013-01-17', '2013-01-18', '2013-01-19',
                '2013-01-20', '2013-01-21', '2013-01-22', '2013-01-23', '2013-01-24', '2013-01-25', '2013-01-26'
            ],
            ['data1', 30, 200, 100, 400, 150, 250, 160, 150, 160, 150, 200, 160, 170, 30, 200, 100, 400, 150, 250, 160, 150, 160, 150, 200, 160, 170],
            ['data2', 130, 340, 200, 500, 250, 350, 320, 200, 500, 250, 350, 300, 310, 130, 340, 200, 500, 250, 350, 320, 200, 500, 250, 350, 300, 310]
        ]
    },
    subchart: {
        show: true,
        onbrush: addLabelToTicks
    },
    axis: {
        x: {
            type: 'timeseries',
            tick: {
                rotate: 25,
                //culling: false,
                format: '%Y-%m-%d'
            }
        }
    }
});