How to have the same top/bottom margins (from the footer/header, if any) and the same left/right margins in the book class

I have the following document. Thanks to the answer https://tex.stackexchange.com/a/272591/ the absolute text-height is 20 cm (text-height+footer+header=20cm).

I would that the left and the right margins to be exactly of the same size, the same for top and the bottom margin.

Added: bottom and top should be the same, including the header and footers.

\documentclass{book}
\usepackage{fancyhdr}
\usepackage{blindtext}

\begin{document}

\pagestyle{fancy}
\fancyhf{}


• The oneside option to the book class should provide the same spacings for the left and right margin – user31729 Oct 13 '15 at 13:15
• bottom and top should be the same, including the header and footers? – user31729 Oct 13 '15 at 13:21
• @ChristianHupfer I apologize for the inconvenience, but your solution to use the option oneside has some conflicts with my header settings, see the complied document, after adding oneside the headers of the pages change. Hence I think adding oneside option is not the solution for this document. – Name Oct 13 '15 at 13:23
• Simply use the option to geometry: centering or marginratio=1:1. – Bernard Oct 13 '15 at 13:26