title: Rstudio Rmarkdown ouput is different than html and pdf
body: <p>I am using RStudio 1.0.44 and I when I run a code chunk in an RMarkdown document, the ouptut looks great but when knit to html or pdf it looks like plain old R console output. </p>
  
  <p>Why the difference?</p>
  
  <p>Example: </p>
  
  <pre><code>library(datasets)
  library(dplyr)
  data &lt;- ToothGrowth
  
  data %&gt;%
     group_by(supp, dose) %&gt;%
     summarise(n=(), mean=mean(len), sd=sd(len))
  </code></pre>
  
  <p>R Markdown:</p>
  
  <pre><code>```{r}
  library(datasets)
  library(dplyr)
  data &lt;- ToothGrowth
  
  data %&gt;%
    group_by(supp, dose) %&gt;%
    summarise(n=n(), mean=mean(len), sd=sd(len))
  ```
  </code></pre>
  
  <p>In RStudio:
  <a href="https://i.stack.imgur.com/StY9R.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/StY9R.png" alt="RStudio chunk"></a></p>
  
  <p>In HTML and PDF:
  <a href="https://i.stack.imgur.com/lg5eZ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/lg5eZ.png" alt="HTML and PDF output"></a></p>