title: Change font size of titles from facet_wrap
body: <h3>Reproducible example</h3>
  
  <pre><code>set.seed(1)
  df &lt;- data.frame(A=rep(c("good","bad"),each=8),
                   B=rep(c("yes","no"),4),
                   C=sample(1:20,16),
                   stringsAsFactors=F) %&gt;%
        group_by(A,B)
  </code></pre>
  
  <h3>Question</h3>
  
  <p><strong>I'd like to change the font size of the titles from <code>facet_wrap</code> ('bad' 'good')</strong></p>
  
  <pre><code>ggplot(df, aes(x=B, y=C)) +
    geom_violin() +
    geom_point() +
    facet_wrap(~A, nrow=1) +
    theme_classic() + 
    theme( axis.text = element_text( size = 14 ),
           axis.text.x = element_text( size = 20 ),
           axis.title = element_text( size = 16, face = "bold" ),
           legend.position="none" )
  </code></pre>
  
  <p>Any ideas? Thanks!</p>