How to change the background color of bars in Highcharts?

 You can change the background color of bars in Highcharts by setting the backgroundColor property of the plotOptions object.

Here's an example:

javascript
Highcharts.chart('container', {
  chart: {
    type: 'bar'
  },
  plotOptions: {
    bar: {
      backgroundColor: '#ff0000' // set the background color of bars to red
    }
  },
  series: [{
    name: 'My Series',
    data: [1, 2, 3, 4, 5]
  }]
});

In this example, we're setting the backgroundColor property of the bar type in the plotOptions object to #ff0000, which is a shade of red. This will change the background color of all bars in the chart to red.

You can also set the background color of individual bars by setting the color property of the data point object. For example:

javascript
series: [{
  name: 'My Series',
  data: [{
    y: 1,
    color: '#ff0000' // set the background color of the first bar to red
  }, {
    y: 2
  }, {
    y: 3
  }, {
    y: 4
  }, {
    y: 5
  }]
}]

In this example, we're setting the color property of the first data point object to #ff0000, which will change the background color of the first bar to red. The other bars will use the default color, which is controlled by the plotOptions.