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The border of the highlighted markers.

<div id="chart"></div>
<script>
$("#chart").kendoChart({
  series: [{
    type: "line",
    markers: {
      visible: true,
      type: "roundedRect"
    },
    highlight: {
      markers: {
        border: {
          color: 'blue',
          width: 2
        }
      }
    },
    data: [1, 2, 3]
  }]
});
</script>

The border color of the highlighted markers.

<div id="chart"></div>
<script>
$("#chart").kendoChart({
  series: [{
    type: "line",
    markers: {
      visible: true,
      type: "roundedRect"
    },
    highlight: {
      markers: {
        border: {
          color: 'red',
          width: 10
        }
      }
    },
    data: [1, 2, 3]
  }]
});
</script>

The border width of the highlighted markers.

<div id="chart"></div>
<script>
$("#chart").kendoChart({
  series: [{
    type: "line",
    markers: {
      visible: true,
      type: "square"
    },
    highlight: {
      markers: {
        border: {
          color: 'green',
          width: 4
        }
      }
    },
    data: [1, 2, 3]
  }]
});
</script>