title: how to plot square shape highchart?
body: <p>am trying to plot a line graph in highchart but its rectangle in shape, how to make it in square shape.</p>
  <p><a href="https://jsfiddle.net/gh/get/library/pure/highcharts/highcharts/tree/master/samples/highcharts/plotoptions/area-fillopacity/" rel="nofollow noreferrer">code here</a></p>
  <pre><code>Highcharts.chart('container', {
  chart: {
      type: 'area'
  },
  xAxis: {
      categories: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']
  },
  
  plotOptions: {
      series: {
          fillOpacity: 0.1
      }
  },
  
  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]
  }]
  });
  </code></pre>
  <p><a href="https://i.stack.imgur.com/EROvz.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/EROvz.png" alt="enter image description here" /></a></p>
  <p>Should be something like above img</p>