如何在合并滚动条宽度的主体内将div精确水平居中？

Question

I´m trying to center a div in the center of a body so the margin to the left and the margin to the right (margin to scrollbar) are the same.

This is what I mean: Website The Top blue header is centered in the middle with same margin left and right.

But when I try to code it myself, the scrollbarwidth is manipulating the margin and sizes...

 body{ width: 100%; height: 100em; background-color: aqua; } div{ width: 100%; height: 100%; background-color: grey; margin-left: auto; margin-right: auto; } 

 <div></div> 

Even if I smaller the width it still has not the same margins:

 body{ width: 98%; height: 100em; background-color: aqua; } div{ width: 100%; height: 100%; background-color: grey; margin-left: auto; margin-right: auto; } 

 <div></div> 

That kid who created that page above did not seem to use any greater css, so wheres the trick ?

Answer 1

This is my Answer to my own Question, I'm not sure if it should be used likes this but I just removed the 100% width from the body.

No idea why css acts like this but I checked that websites source and it did not has any body width so I just tried that.

Answer 2

You can use viewport widths instead of percentage and set margins like this:

body {width:100vw}
div {margin:0 auto}