Why is the nav background ihavimg a space between the screen size , like I want to it to the school

Question

https://code.sololearn.com/W0ij4Wy7eyjq/?ref=app

Answer 1

Write this in CSS before body
*{
padding:0px;
margin :0px;
}

Answer 2

It's enough to write:
body { margin:0; }

this set only the default body margin to zero, while * in Emmanuel Ezoba answer select and apply zero margin and padding to all elements of the page ^^