title: How to add border to code blocks in generated beamer pdf from Markdown using Pandoc
body: <p>I've found how to add line numbers by writing,</p>
  
  <pre><code>```{.c .numberLines}
  int x = 1;
  int y = x;
  ```
  </code></pre>
  
  <p>But wonder how to add a border to the code blocks.</p>