Defining left/right overhang with \cellcolor

Question

I want to highlight one row and one column in a table. The column is no problem. However, the colour panels of the outermost left and right cell in the row overhang the table's borders if I use @{} in the tabulardefinition.

\documentclass{scrartcl}
\usepackage{colortbl,booktabs}
\begin{document}
\begin{table}[h]
  \setlength{\aboverulesep}{0pt} % align \bottomrule nicely to coloured cell
  \setlength{\belowrulesep}{0pt} % align \toprule nicely to coloured cell
  \setlength{\extrarowheight}{.75ex} % make up for lost ruleseps

  \begin{tabular}{@{}c>{\columncolor[gray]{.9}}cc@{}} \toprule
                        a & b & c \\
                        d & e & f \\
    \rowcolor[gray]{.9} g & h & i \\
    \bottomrule
  \end{tabular}
\end{table}
\end{document}

The problem is obvious:

Using \rowcolor[gray]{.9}[0pt][0pt] to reduce overhang is not an option as the row would then not be fully highlighted anymore.

What I tried so far

1. Redefining the highlighted row like the following prints [0pt] into the cell and doesn't work, although it was suggested here.

   \rowcolor[gray]{.9}\cellcolor{white}\cellcolor[gray]{.9}[0pt] g & h & i \\
   

2. Redefining the highlighted row like this also doesn't work:

   \rowcolor[gray]{.9}[0pt][0pt] g & \cellcolor[gray]{.9} h & i \\
   

   The middle cell stays highlighted like there was only \rowcolor[gray]{.9}[0pt][0pt] defined…

Is there any other possibilty to trim the colour panels to align with \bottomrule to the left and to the right?

Answer 1

One way is to fix column widths. I am not sure if this is a very elegant way.

\documentclass{scrartcl}
\usepackage{colortbl,booktabs}
\begin{document}

\newcolumntype{C}[1]{>{\centering\let\newline\\\arraybackslash\hspace{0pt}}p{#1}}

\begin{table}[h]
\setlength\tabcolsep{0pt}
  \begin{tabular}{C{1em}>{\columncolor[gray]{.9}} C{1em} C{1em}} \toprule
                        a  & b & c \\
                        d & e & f \\
    \rowcolor[gray]{.9} g & h & i \\
    \bottomrule
  \end{tabular}
\end{table}
\end{document}
\end{document}

Answer 2

\documentclass{scrartcl}

\usepackage{booktabs}
\usepackage[table]{xcolor}

\colorlet{tablerowcolor}{yellow}%\colorlet{tablerowcolor}{gray!10}

\newcommand*{\ct}[1]{\multicolumn{1}{>{\columncolor{tablerowcolor}}c}{#1}}
\newcommand*{\fct}[1]{\multicolumn{1}{>{\columncolor{tablerowcolor}\hspace*{-\tabcolsep}}c}{#1}}
\newcommand*{\lct}[1]{\multicolumn{1}{>{\columncolor{tablerowcolor}}c<{\hspace*{-\tabcolsep}}}{#1}}
\newcommand*{\cfct}[1]{\multicolumn{1}{>{\columncolor{tablerowcolor}[\dimexpr\tabcolsep-\cmidrulekern\relax][\tabcolsep]\hspace*{-\tabcolsep}}c}{#1}}
\newcommand*{\clct}[1]{\multicolumn{1}{>{\columncolor{tablerowcolor}[\tabcolsep][\dimexpr\tabcolsep-\cmidrulekern\relax]}c<{\hspace*{-\tabcolsep}}}{#1}}

\begin{document}

\begin{table}[h]
    \setlength{\aboverulesep}{0pt} % align \bottomrule nicely to coloured cell
    \setlength{\belowrulesep}{0pt} % align \toprule nicely to coloured cell
    \setlength{\extrarowheight}{.75ex} % make up for lost ruleseps

    \begin{tabular}{ @{}r@{} }
        \\
        reference \\
        wrong alignment if overhang \\
        fitted to \texttt{\textbackslash midrule} \\
        fitted to \texttt{\textbackslash cmidrule(lr)} \\
    \end{tabular}
    %
    \begin{tabular}{ @{}*{3}{c}@{} }
        \toprule
        test    & test & test    \\
        \midrule
              a & b    &       c \\
        \ct   a & b    & \ct   c \\
        \midrule
        \fct  a & b    & \lct  c \\
        \cmidrule(lr){1-3}
        \cfct a & b    & \clct c \\
        \bottomrule
    \end{tabular}
\end{table}

\end{document}