title: how to set the bold font style in Plotly
body: <p>When using the Plotly, I can set the title font in the layout part as follow. </p>
  
  <pre><code>titlefont=dict(size =14, color='black', family='Arial, sans-serif')
  </code></pre>
  
  <p>My question is How to set the font as Bold. Thanks</p>