title: How to create a complexe header with multi row + nav
body: <p>I started with bootstrap and despite official documentation I'm stuck for a complex case .
  Here's what I want to do :</p>
  
  <p><img src="https://i.stack.imgur.com/BcD8g.png" alt="enter image description here"></p>
  
  <p>I know how to make lines, navbar, show and hide them but I wonder how to make the header version of the site and switch to a single line. </p>
  
  <p>Does anyone have an idea? </p>