Highcharts with markers

HTML

<script src="https://code.highcharts.com/highcharts.js"></script>
<script src="https://code.highcharts.com/modules/exporting.js"></script>

<div id="container"></div>


<svg width="200" height="200">
    <defs>
        <marker id="arrow" refX="4" refY="2.5" markerWidth="5" markerHeight="5" orient="auto">
            <path d="M0,0 L5,2.5 L0,5 Z" class="arrow"></path>
        </marker>
    </defs>
</svg>

CSS

#container {
    min-width: 300px;
    max-width: 800px;
    height: 300px;
    margin: 1em auto;
}

.arrow {
    fill: #7cb5ec;
}

.series-direction path.highcharts-graph {
    marker-start: url(#arrow);
    marker-mid: url(#arrow);
    marker-end: url(#arrow);
}

JavaScript

Highcharts.chart('container', {

    title: {
        text: 'SVG markers in Highcharts'
    },

    xAxis: {
        categories: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun',
            'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'
        ]
    },

    series: [{
        data: [29.9, 71.5, 106.4, 129.2, 144.0, 176.0, 135.6, 148.5, 216.4, 194.1, 95.6, 54.4],
        type: 'spline',
        className: 'series-direction',
        marker: {
            enabled: false
        }
    }]

});