Why can a small scroll appear if everything fits in the browser window?

Question

css

A small scroll appears, everything fits into the browser window, it does not show indents in the developer ...

Answer 1

100% some nested tag has a width larger than the window. Watch carefully. Step by step remove the blocks in the inspector and find the reason.

Answer 2

width:100%; put - everything will pass

Answer 3

To the very beginning of the style
*{
margin: 0;
padding: 0;
}