title: sticky-top full-width dropdown on hover navbar
body: <p>I m a newbie on bootstrap techniques and i m trying to compine two different styles in a navbar. 
  the first is about sticky navbar and the second Full-width dropdown navbar, both found on an educational website.</p>
  
  <p><a href="https://www.w3schools.com/howto/tryit.asp?filename=tryhow_css_mega_menu_responsive" rel="nofollow noreferrer">https://www.w3schools.com/howto/tryit.asp?filename=tryhow_css_mega_menu_responsive</a>
  <a href="https://www.w3schools.com/howto/tryit.asp?filename=tryhow_js_navbar_sticky" rel="nofollow noreferrer">https://www.w3schools.com/howto/tryit.asp?filename=tryhow_js_navbar_sticky</a></p>
  
  <p>i ve tried several changes with no result and i dont have much knowledge.
  any help would be much appreciated.
  thanks in advance</p>