title: Center menu items in responsive navbar
body: <p>w3schools has a nice example of a nav bar that will respond to a smaller screen:</p>
  
  <p><a href="https://www.w3schools.com/howto/tryit.asp?filename=tryhow_js_topnav" rel="nofollow noreferrer">https://www.w3schools.com/howto/tryit.asp?filename=tryhow_js_topnav</a></p>
  
  <p>How can I have the menu items centered, instead of aligned to the left? Setting <code>ul.topnav li {float: center;}</code> just makes them stack vertically.</p>