Why my tabular does not have the padding

Question

I tried to insert on a document a table (tabular) but the rendering of the code is a table without padding. Where is the error?

code:

\documentclass[11pt,a4paper,sans]{moderncv}
\moderncvstyle{casual}

\moderncvcolor{blue} 
\usepackage[utf8]{inputenc}
\usepackage[scale=0.77]{geometry}
\usepackage{multicol}
\usepackage{fancyhdr}
\usepackage{lastpage}

\usepackage{booktabs}
\usepackage{tabularx}

\usepackage{graphicx}

\pagestyle{fancy}
\fancyhf{}

...

\cvitemwithcomment{}{
\begin{tabular}{@{}llll@{}}
\toprule
XXXXXXXXXX & MMMMMM       & XXXXXXXXXXX & MMMMMMMM \\ \midrule
Lorem      & Ipsum       & dolor       & sit      \\
amet,      & consectetur & adipiscing  & elit.    \\
Aenean     & a           & lacus       & sit      \\ \bottomrule
\end{tabular}
}
{}

the result is:

Answer 1

Since you're using \cvitemwithcomment, I'm assuming you're using the moderncv document class.

The length responsible for the gap between columns in a tabular is \tabcolsep. This is defined in latex.ltx - the LaTeX kernel - but is specifically set within the document class that you use. For example, article uses

\setlength\tabcolsep{6\p@}

However, moderncv has the following comments inside moderncv.cls:

% not set on purpose
%\setlength\arraycolsep{5\p@}
%\setlength\tabcolsep{6\p@}
%\setlength\tabbingsep{\labelsep}

So, it purposely does not set any changes to \tabcolsep (and others), keeping them at their default length which is 0pt when it is defined.

If you wish to have some padding, you have the following options:

1. Add

   \setlength{\tabcolsep}{6pt}
   

   anywhere in your preamble. Note that this may affect other components constructed by the document class wherever it uses a tabular.

2. Use

   \begingroup
   \setlength{\tabcolsep}{6pt}
   % <your tabular content>
   \endgroup
   

   to localise the scope of the \tabcolsep changes to the specific tabular where you want to use it.

Option 2 would be advisable, since the class uses tabulars quite regularly.