How to hide navbar and footer of blogger

navbar (showing at top):

Footer:  

Here I am trying to hide using below steps:

Go To Theme ==> Click Customize Drop Down ==> Click Edit HTML ==> Add Below Css Code

Code Snippet

#Attribution1 { display: none !important; visibility: hidden !important; } #navbar { display: none !important; visibility: hidden !important; } #b-navbar { display: none !important; visibility: hidden !important; }