\longtable 列太宽。为什么？

Question

为什么第二列太宽（cmidrule？）？我该怎么办？

\documentclass[11pt,a4paper]{article}

\usepackage{makecell}
\usepackage[utf8]{inputenc}
\usepackage[left=1.3cm,right=1.3cm,top=1.8cm,bottom=4.0cm,marginparwidth=3.4cm]{geometry}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{numprint}

\usepackage{textcomp, gensymb}
\usepackage{rotating}
\usepackage{booktabs}
\usepackage{array}
\usepackage{caption}
\usepackage{longtable}


\begin{document}
\begin{longtable}{ll}
\multicolumn{1}{l}{\rotatebox[origin=l]{90}{\makecell{Diameter\\base}}} &
\multicolumn{1}{l}{\rotatebox[origin=l]{90}{\makecell{Door\\position}}} \\
\cmidrule(lr){1-1}
\cmidrule(lr){2-2}
\endfirsthead
\multicolumn{1}{l}{\rotatebox[origin=l]{90}{\makecell{Diameter\\base}}} &
\multicolumn{1}{l}{\rotatebox[origin=l]{90}{\makecell{Door\\position}}} \\
\cmidrule(lr){1-1}
\cmidrule(lr){2-2}
\endhead
\multicolumn{2}{c}{ Continued on next page}
\endfoot
\endlastfoot
175.0 & 4.00\\
210.0 & 5.00\\
\end{longtable}
\end{document}