Big header and page margins

I am trying to insert a big header, but it pushes the text and footer.

With short header I get this:

But when I increase header size the text and footer move.

MWE:

\documentclass[headheight=24pt]{article}\usepackage[showframe]{geometry}\usepackage{fancyhdr}\renewcommand{\headrule}{}\pagestyle{fancy}\fancyhf{}\chead{\vspace{.5cm}Header\vspace{.5cm}}\cfoot{Footer}\begin{document}First page text\footnote{first page footnote}\newpage\end{document}