title: Simple Bootstrap responsive header (navbar) drops on resize
body: <p>When you view the page with a wide browser window, it looks fine. If you resize the window to make it skinny, the header suddenly drops by 60px, which is equal to the body's padding-top. To make this page I started with a simple Bootstrap template and stripped out most of the content. Why is this happening?</p>
  
  <p><img src="https://i.stack.imgur.com/uYbg8.png" alt="screenshot"></p>