<div id="chart"></div>
<script>
$("#chart").kendoChart({
  series: [{
    type: "line",
    name: "Series A",
    data: [1, 2, 3],
    legendItem: {
      markers: {
        border: {
          color: "red",
          width: 2
        }
      }
    }
  }]
});
</script>