如何使超长的并列tabular表格居中显示 about forum HOT 4 CLOSED

\documentclass[a4paper,twoside,onecolumn,12pt]{ctexrep}
\usepackage{titlesec}
\usepackage{indentfirst,ulem}
\usepackage{float,graphicx}
\usepackage{multirow,booktabs,makecell,amssymb,array}
\usepackage[a4paper, hmargin=1.5cm, vmargin=1cm, headheight=0pt, ignorehead]{geometry}

% 重设定chapter间距
\ctexset{
    chapter={
        beforeskip=1ex,
        afterskip=2ex
    },
    section={
        beforeskip=1ex,
        afterskip=.6ex
    },
    subsection={
        beforeskip=0pt,
        afterskip=.4ex
    }
}

% 重定义文章字体
%\setmainfont[BoldFont=Dream Han Serif CN W20]{Dream Han Serif CN W7}
%\setCJKmainfont{Dream Han Serif CN W7}[BoldFont=Dream Han Serif CN W20]

% 行间距设定
\setlength{\parindent}{1em}

\begin{document}
% 题目
\title{\Huge{\textbf{山二医入学与生活指南}\\\normalsize{（简称：三二一新指南）}\\\large{浮烟山校区专用}}}
\bigbreak
\author{LinkChou\thanks{第2.2.3版，遵循CC BY-SA 4.0协议。}\and 山二医校园频道}
\maketitle

% 段落间距重设定
\setlength{\parskip}{.75em plus 5pt minus 5pt}

%chapter12
\chapter[老乡群号汇总]{老乡群号汇总}

\vspace*{2em}

\begin{center}
  测试居中效果\\
  XXX\qquad XXX \\
\end{center}

\noindent\makebox[\textwidth][c]{%
    \begin{tabular}[t]{|w{c}{4em}|w{c}{6em}|}
        \Xhline{1.2pt}
        \multicolumn{2}{|c|}{山东省老乡QQ群号} \\
        \Xhline{1.2pt}
        济南   & 123456789                \\
        \hline
        青岛1群 & 123456789                \\
        \Xhline{1.2pt}
    \end{tabular}%
    \qquad
    \begin{tabular}[t]{|w{c}{4em}|w{c}{6em}|}
        \Xhline{1.2pt}
        \multicolumn{2}{|c|}{省外地区老乡QQ群号} \\
        \Xhline{1.2pt}
        重庆   & 123456789                 \\
        \hline
        江苏   & 123456789                 \\
        \Xhline{1.2pt}
    \end{tabular}%
}
\end{document}