title: How can I simply add a css file to change the background color for my shiny app
body: <p>I'm re-asking my question from...</p>
  
  <p><a href="https://stackoverflow.com/questions/29360182/how-do-i-find-my-shiny-apps-existing-css">How do I find my shiny app&#39;s existing css?</a></p>
  
  <p>...to generalize it for useRs that don't really get css yet.  I've spent time reading over the rstudio css guide at <a href="http://shiny.rstudio.com/articles/css.html" rel="nofollow noreferrer">http://shiny.rstudio.com/articles/css.html</a> but it still doesn't click.  I understand a couple things though that I think means I'm 90% there. </p>
  
  <ol>
  <li>the css file has to be linked in ui.r and from the theme argument in either the fluidPage or navbarPage function. </li>
  <li>Adding a very sparse css file to add a background color breaks the existing css. </li>
  </ol>
  
  <p>So, my question is what is the simplest implementation of css to change the background color of the example histogram app at the shiny gallery at <a href="http://shiny.rstudio.com/gallery/faithful.html" rel="nofollow noreferrer">http://shiny.rstudio.com/gallery/faithful.html</a>. </p>
  
  <p>I think the answer to this question would help along some shiny app developers that are new to css like myself. </p>