title: How to add formatting when exporting to excel in rails
body: <p>This is when using a view file to generate an excel file. like:
  in controller:</p>
  
  <pre><code>headers['Content-Type'] = "application/vnd.ms-excel"
  headers['Content-Disposition'] = 'attachment; filename="report.xls"'
  </code></pre>
  
  <p>then in view:</p>
  
  <pre><code>&lt;table&gt;&lt;tr&gt;&lt;td&gt;foo&lt;/td&gt;&lt;td&gt;bar&lt;/td&gt;&lt;/tr&gt;&lt;table&gt;
  </code></pre>
  
  <p>Is it possible to add formatting such as color to cells? like:</p>
  
  <pre><code>&lt;td style="background-color=red"&gt;foo&lt;/td&gt;
  </code></pre>