title: Output table width in Rmarkdown
body: <p>I'm using Rmarkdown to create a document. I want to include markdown tables, but they are all scaled to the width of the page. I'd like to specify a relative width of say... 40% for the table. I've tried various options associated with the following:</p>
  
  <pre><code>library(pander)
  pandoc.table(head(cars))
  
  library(xtable)
  print(xtable(head(cars)), type="html")
  
  library(knitr)
  kable( head(cars), format="markdown")
  </code></pre>
  
  <p>Any ideas?</p>
  
  <p>Thanks</p>