title: kableExtra: adjust font face and background of add_header_above()
body: <p>In a table generated with <code>kableExtra()</code> I would like to adjust the font face and background of the two top rows added with <code>add_header_above()</code>.</p>
  <p>The MWE provided below allows making adjustments to the top row of the original table.
  However, my goal is that</p>
  <ul>
  <li>the upper top row added has a <strong>bold</strong> font face and a colored background, and</li>
  <li>the lower top row added has an <em>italic</em> font face.</li>
  </ul>
  <p>The table is included in a Rmarkdown document which is knitted both to PDF/LaTex and HTML.</p>
  <h2>MWE</h2>
  <pre><code>mtcars[1:3,1:4] %&gt;% kable() %&gt;% 
      kable_styling(latex_options = c(&quot;striped&quot;, &quot;scale_down&quot;)) %&gt;% 
    # add column labels
    add_header_above(c(&quot; &quot; = 1, &quot;Features&quot; = 2, &quot;Features&quot; = 2)) %&gt;% 
    add_header_above(c(&quot; &quot; = 1, &quot;Properties A&quot; = 2, &quot;Properties B&quot; = 2)) %&gt;% 
    # adjust font face and backgroun
    row_spec(row = 0, italic = T) %&gt;% 
    row_spec(row = 0, background = &quot;orange&quot;) 
  </code></pre>
  <p><a href="https://i.stack.imgur.com/Lnh75.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Lnh75.png" alt="enter image description here" /></a></p>