title: How to change background color of the chart?
body: <p>Use this c3js and d3js libraries and I want to change the background color of the complete chart.
  My example seems not to work.</p>
  
  <p>c3js (v. c3-0.6.7)</p>
  
  <p>d3js (v. d3-5.7.0)</p>
  
  <pre><code>&lt;style type="text/css"&gt;
   #mychart { background-color: gray; }
  &lt;/style&gt;
  
     [...] 
  
  &lt;div id="mychart" &gt;&lt;/div&gt;
  
     [...] 
  
  &lt;script type="text/javascript"&gt;
     [...] 
     var chart = c3.generate({
         bindto: '#mychart',
     [...] 
  &lt;/script&gt; 
  </code></pre>