Different headers for first page and following pages even and odd

Question

What I would like to achieve is a (fairly high) header in the first page and alternate headers with different heights for even and odd in the subsequent pages.

I tried Werner's solution from this page, but I have the problem that, like I said, the subsequent headers are of different heights in even and odd pages. Here is my document, although it's not really minimal

\documentclass[11pt,a4paper,twoside]{article}
\usepackage[ngerman]{babel}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{xcolor}
\usepackage{xltabular,multirow}
\usepackage{graphicx}
\usepackage{siunitx}
\usepackage{fancyhdr}
\usepackage{lastpage}
\usepackage[bottom]{footmisc}
\usepackage{blindtext}
\usepackage[left=2.00cm, right=3.00cm, top=2cm, bottom=2.0cm, headsep=1.50cm]{geometry} % Tried with other bottom margins. The footer disappears at the bottom of the page.
\usepackage{hyperref}
\hypersetup{
    colorlinks=true,
    linkcolor={red!60!black},
    citecolor={blue!50!black},
    urlcolor={blue!80!black},
}
\fancyhf{}
\sisetup{output-decimal-marker={,},group-minimum-digits=4}
% Header for first page
\fancypagestyle{ersteabph}{
    \fancyhf{}% Clear header/footer
        \renewcommand{\headrulewidth}{0pt}% Remove header rule
        \setlength{\headheight}{160pt}
        \fancyhead[C]{\begin{xltabular}{\textwidth}{p{9cm} p{8mm} X}
                \raisebox{-\height}[0pt][0pt]{\textbf{{\Large Mybeautifulschool}}} & & \raisebox{-\height}[0pt][0pt]{\textbf{\Large Arbeitsblatt Physik}}\newline \raisebox{-\height}[0pt][0pt]{\textbf{\Large Elektrisches Feld}}\
                Name: & & GPH1\
                Datum: & & Seite \thepage/\pageref{LastPage}
            \end{xltabular}\rule{\linewidth}{.4pt}
        }
}
% Header for subsequent pages
\fancypagestyle{abph}{
    \fancyhf{}
    \setlength{\headheight}{120pt}
    \renewcommand{\headrulewidth}{0pt}
    \fancyhead[CO]{\begin{xltabular}{\linewidth}{p{9cm} p{8mm} X}
            \raisebox{-\height}[0pt][0pt]{\textbf{{\Large Mybeautifulschool}}} & & \raisebox{-\height}[0pt][0pt]{\textbf{\Large Arbeitsblatt Physik}}\newline \raisebox{-\height}[0pt][0pt]{\textbf{\Large Elektrisches Feld}}\
            & & Seite \thepage/\pageref{LastPage}
            \end{xltabular}}
    \fancyhead[RE]{\raisebox{-\height}[0pt][0pt]{\thepage/\pageref{LastPage}}}
}
\pagestyle{abph}
\setlength{\parindent}{0pt}
\renewcommand{\arraystretch}{2.50}
\author{Myself}
\begin{document}
%\vspace*{3cm}

\section*{Versuch: die Energie des Kondensators.}

\thispagestyle{ersteabph}

\begin{minipage}[b]{0.5\textwidth}
    \includegraphics[width=0.98\linewidth]{example-image-a}
\end{minipage}\hspace{0.1cm}%
\begin{minipage}[b]{0.5\textwidth}
    \includegraphics[width=0.98\linewidth]{example-image-b}
\end{minipage}

\section*{Versuchsbeschreibung}

In diesem Versuch wollen wir die Abhängigkeit der in einem Kondensator gespeicherten Energie von der Spannung und von der Kapazität untersuchen. Dafür laden wir einen Kondensator zu einer gewissen Spannung und lassen ihn auf einem elektrischen Motor entladen. Am Motor hängt ein Gewicht mit gegebener Masse $m$. Der Motor kommt zum Laufen und hebt das Gewicht zu einer gewissen Höhe $h$. Die potentielle Energie $E_{\mathrm{pot}}$, die das Gewicht beim Anheben gewinnt, ist zur gespeicherten Energie im Kondensator proportional.\\

Der Versuch besteht aus zwei Teilen: zuerst wird ein Kondensator auf verschiedene Spannungen geladen. Die angegebene Spannung und die durch das Gewicht erreichte Höhe werden in eine Tabelle eingetragen. Dann werden Kondensatoren unterschiedlicher Kapazitäten auf die gleiche Spannung geladen und wir notieren wieder in eine Tabelle die Kapazität und die erreichte Höhe.\\ 

Beim Versuch ist auf folgendes zu achten:

\begin{itemize}
    \item Der Motor hat leider keine Bremse, sodass das Gewicht wieder nach unten kommt, wenn es nicht angehalten wird. Warte, bis das Gewicht die maximale Höhe erreicht und halte es dann an dieser Stelle, sodass die Höhenmessung durchgeführt werden kann.
    \item Beim ersten Teil wählen wir einen Kondensator mit Kapazität \SI{10}{\milli\farad} und die Ladespannungen \qtylist{4;6;8;10}{V}. Überschreitet bitte nicht die Spannung \SI{10}{V}, da sonst das Gewicht zu hoch kommt und am Ösen klemmt (außerdem würde das Ergebnis dadurch gefälscht).
    \item Beim zweiten Teil wählen wir Kondensatoren mit Kapazität \qtylist{4.7;5;6.7;10}{\milli\farad} und die Spannung von \SI{9}{V}. Auch diese Werte wurden so gewählt, dass die Messdaten eine gute Auswertung ermöglichen.
\end{itemize}

\Blindtext[3][3]

\section*{Durchführung}


\end{document}

I also tried without adding the \setlength{\headheight} (suggested by the warnings), but leaving the \vspace*{} at the beginning of the document per Werner's answer in the linked question. That solution, however, has the problem that the header of the odd pages is too high and ends up in the text. I can't keep adding \vspace*{}s because I don't know in advance where a page ends (or at least it's not elegant).

Another thing I tried is a solution with \usepackage[pagestyles]{titlesec}, but that didn't work either (I can paste my not-so-minimal example of that if you want me to).

So basically:

• if I add the \setlength{\headheight}, I have the problem that the top margins don't all look the same and the bottom margin is not right.
• if I use the \vspace*{}s, then the bottom margin is right, but I have to insert it manually and change it every time I add or remove something in the text (unless there is an automated way to do it that I don't know).

I'm ready to do away with the xltabulars in the headers, if there is another easy way to line up the lines of the header properly.

I am out of ideas to try and open to suggestions.

EDIT:

By the way, my question sounds exactly like this one, but that one is closed and has no answer.

Answer 1

You can adjust the page layout using the shipout/after hook.

\documentclass{article}
\usepackage{showframe}
\makeatletter
  \newdimen\evenoddheadheightdiff
  \def\addtoheadheight#1{%
    @tempdima=#1\relax
    \global\advance\headheight@tempdima
    \global\advance\textheight-@tempdima
  }
  \AddToHook{shipout/after}{%
    \ifodd\thepage
      \addtoheadheight{\evenoddheadheightdiff}%
    \else
      \addtoheadheight{-\evenoddheadheightdiff}%
    \fi
  }
\makeatother
\evenoddheadheightdiff=10ex\relax
\begin{document}
\strut\clearpage
\strut\clearpage
\strut\clearpage
\strut\clearpage
\strut\clearpage
\strut\clearpage
\end{document}

Then you just have to plug in the desired headers using fancyhdr or scrlayer-scrpage or the like. For example:

\documentclass[twoside]{article}
\usepackage{fancyhdr}
\fancypagestyle{first}{
  \fancyhead[C]{\huge Something tall for the first page}
}
\fancypagestyle{default}{
    \fancyhead[OC]{\huge Something very tall}
    \fancyhead[ER]{Something not so tall}
}
\pagestyle{default}
\makeatletter
  \newdimen\evenoddheadheightdiff
  \def\addtoheadheight#1{%
    @tempdima=#1\relax
    \global\advance\headheight@tempdima
    \global\advance\textheight-@tempdima
  }
  \AddToHook{shipout/after}{%
    \ifodd\thepage
      \addtoheadheight{\evenoddheadheightdiff}%
    \else
      \addtoheadheight{-\evenoddheadheightdiff}%
    \fi
  }
\makeatother
\evenoddheadheightdiff=-10ex\relax
\addtoheadheight{-\evenoddheadheightdiff}
\begin{document}
\thispagestyle{first}
\strut\clearpage
\strut\clearpage
\strut\clearpage
\strut\clearpage
\strut\clearpage
\strut\clearpage
\end{document}

---

You can easily extend this to have a different \headheight on the first page (or any other page, for that matter). I would recommend changing the interface if you do this a lot, depending on your application. This answer was just meant to show you the way. Here's one way to do it with the given interface.

\documentclass[twoside]{article}
\usepackage{fancyhdr}
\usepackage{showframe}
\fancypagestyle{first}{
  \fancyhead[C]{\huge Something tall for the first page}
}
\fancypagestyle{default}{
    \fancyhead[OC]{\huge Something very tall}
    \fancyhead[ER]{Something not so tall}
}
\pagestyle{default}
\makeatletter
  \newdimen\evenoddheadheightdiff
  \def\addtoheadheight#1{%
    @tempdima=#1\relax
    \global\advance\headheight@tempdima
    \global\advance\textheight-@tempdima
  }
  \AddToHook{shipout/after}{%
    \ifodd\thepage
      \addtoheadheight{\evenoddheadheightdiff}%
    \else
      \addtoheadheight{-\evenoddheadheightdiff}%
    \fi
  }
\makeatother
\evenoddheadheightdiff=-10ex\relax
\newdimen\evenfirstpageheightdiff
\evenfirstpageheightdiff=-30ex\relax
\addtoheadheight{-\evenfirstpageheightdiff}
\AddToHookNext{shipout/after}{%
  \addtoheadheight{\evenfirstpageheightdiff}%
  \addtoheadheight{-\evenoddheadheightdiff}
}
\begin{document}
\thispagestyle{first}
\strut\clearpage
\strut\clearpage
\strut\clearpage
\strut\clearpage
\strut\clearpage
\strut\clearpage
\end{document}

Answer 2

For the first page the simplest solution is usually to have an empty header and then put the "header" as normal text just at the beginning of the document. This saves the hassle of having a different \headheight.

Changing \headheight mid-document is tricky business sowieso (anyway), and trying to have the \textheight being changed accordingly is even trickier. So my solution doesn't do that but uses a fixed \headheight. On even pages where a tall header is placed, I first put the header in a \raisebox to trick fancyhdr into believing that it isn't tall, so that it will not complain, and to position it properly. And moreover on even pages I add some additional vertical space on the top of the text (i.e. just under the header) with \vspace (or a zero-width \rule). I do this with \afterpage, which is repeated on each page, and just checks if the page number is even to put that space there).

\documentclass[twoside]{article}
\usepackage{lipsum}
\usepackage{fancyhdr}
\usepackage{afterpage}
\usepackage{graphicx}
\fancypagestyle{firstpage}{%
  \fancyhead{}
}
\pagestyle{fancy}
\setlength{\headheight}{16pt}
\fancyhead[LE]{\raisebox{-10pt}[0pt][0pt]{\parbox[t]{\headwidth}{\Huge EVEN PAGE HEADER\SECOND LINE}}}
\fancyhead[LO]{ODD PAGE HEADER}
\fancyfoot[C]{\thepage}
\renewcommand{\headrulewidth}{0pt}
\newcommand{\nextpage}{%
  \ifodd\value{page}\else\vspace*{30pt}\fi
  % Other possibility:
  % \ifodd\value{page}\else\rule{0pt}{30pt}\fi
  \afterpage{\nextpage}
}
\begin{document}
\thispagestyle{firstpage}
\afterpage{\nextpage}
\includegraphics[height=100pt]{example-image}
\vspace{20pt}
\lipsum[1-4]
\begin{figure}
  \centering
\includegraphics{example-image-a}
\vspace{5cm}
  \caption{This is the figure}
\end{figure}
\lipsum[1-20]
\end{document}