title: How to change the tooltip background color in JQuery Sparklines
body: <p>Is there a way to change the default background color of the tooltip in jQuery Sparklines? I have not been able to find a simple solution to this and there hasn't seem to be a similar question for sparklines tooltips. I would like to change the background color from the transparent default color to a solid grey. </p>
  
  <p>I am using a custom tooltipFormatter to create the text within the tooltip, e.g.</p>
  
  <pre><code>$('#sparkline').sparkline(data, {
    type: 'bar',
    tooltipFormatter: function(sparkline, options, fields) {
       //&lt;span&gt;Stuff&lt;/span&gt;
    }
  });
  </code></pre>
  
  <p>Thanks!</p>