title: Highcharts, set legend height dynamically
body: <p>I would like to set the height of the legend dynamically, so when the container gets resized, the legend height will be adjusted automatically.
  Ideally, the height of the legend should be half of the height of the charts container.</p>
  
  <p>fiddle: 
  <a href="https://jsfiddle.net/rredondo/awac1dw8/" rel="nofollow noreferrer">https://jsfiddle.net/rredondo/awac1dw8/</a></p>
  
  <p>Note that as the container gets smaller, the chart's plot area also becomes smaller until it disappears because the legend is taking up the space. This is the behavior I want to avoid. 
  Also, I tried setting <code>maxHeight</code> to some number. The problem with this approach is that it is not dynamic, and it wastes a lot of space if the value is too small.</p>
  
  <p>The legend options are:</p>
  
  <pre><code>legend: {
         align: 'center',
         verticalAlign: 'bottom',
         layout: 'vertical',
         enabled: true,
         //maxHeight: 150
  },
  </code></pre>
  
  <p>The layout must be set to vertical, and the legend must be positioned below the chart.</p>