Source google image: http://www.opentuto.com/wp-content/uploads/2016/09/Cr%C3%A9er-un-site-web-responsive-en-HTML-CSS-et-Bootstrap-4-opentuto.png
Exemple site web avec bootstrap
Source google image: http://www.opentuto.com/wp-content/uploads/2016/09/Cr%C3%A9er-un-site-web-responsive-en-HTML-CSS-et-Bootstrap-4-opentuto.png