title: Adjust size of leaflet map in rmarkdown html
body: <p>I'd like to change the height and width of <code>leaflet</code> map outputs in html document. Is there a simple way to do this in R markdown without getting into whole CSS business?</p>
  
  <pre><code>```{r}
  library(leaflet)
  library(dplyr)
  
  m &lt;- leaflet() %&gt;% setView(lng = -71.0589, lat = 42.3601, zoom = 12)
  m %&gt;% addTiles() 
  ```
  </code></pre>
  
  <p>Ideally, I want the width of map to be the same width of code block as shown below.</p>
  
  <p><a href="https://i.stack.imgur.com/NzgJE.png" rel="noreferrer"><img src="https://i.stack.imgur.com/NzgJE.png" alt="enter image description here"></a></p>