如何使页眉顶部精确对齐在页面顶部？

Question

我的任务是（自动）渲染具有可选高度的标题。因此我无法理解逻辑 - 标题高度如何工作？

我的标题包含-与我输入的内容parbox相同 ，因此当高度为 128 时，我得到了这张图片：heightheadheight

当高度为 32 时，我得到了

所以我的问题是：如何使页眉顶部与页面顶部精确对齐？

\documentclass{book}
\usepackage{fancybox,fancyhdr}
\usepackage[T1]{fontenc}
\usepackage[dvipsnames]{xcolor}
\usepackage{fixltx2e}
\usepackage[left=72pt,right=72pt,
    headheight=124pt,
    voffset = 0pt,
    textheight =540pt
    ]{geometry}
\usepackage{array}
\usepackage{showframe}
\fancyhf{}\fancyhead[C]{ \noindent\sbox{0}{\parbox{\textwidth}{\noindent\begin{tabular}{L{\textwidth}{p}}Non-disclosure agreement (NDA)\end{tabular}}}
\ifdim\dimexpr\ht0+\dp0<124pt
\dp0\dimexpr124pt-\ht0\fi
\makebox{\usebox{0}}\\}
\begin{document}
    \pagestyle{fancy}
    test
 \end{document}

Answer 1

设置为您的和top的总和。注释掉虚假空格并删除表中的：headheight\headsep\tabcolsep

\documentclass{book}
\usepackage{fancybox,fancyhdr}
\usepackage[T1]{fontenc}
\usepackage[dvipsnames]{xcolor}

\usepackage[left=72pt,right=72pt,
    headheight=124pt,
    top=\dimexpr124pt+\headsep\relax,% <- added
    textheight =540pt
    ]{geometry}
\usepackage{array}


\newcolumntype{L}[2]{>{\raggedright\arraybackslash}{#2}{#1}}

\fancyhf{}
\fancyhead[C]{%
  \sbox{0}{\parbox{\textwidth}{\begin{tabular}{@{}L{\textwidth}{p}@{}}Non-disclosure agreement (NDA)\end{tabular}}}%
  \ifdim\dimexpr\ht0+\dp0<124pt \dp0\dimexpr124pt-\ht0\fi
  \makebox{\usebox{0}}%
}

\usepackage{lipsum}
\usepackage{showframe}
\begin{document}
\pagestyle{fancy}
\lipsum
\end{document}