[Tex/LaTex] How to color only one cell in a multicolumn table

Question

I have the following table in LaTeX.

\documentclass{beamer}
\usepackage{multirow}
\usepackage{xcolor,colortbl}

\begin{document}

\begin{frame}
\frametitle{Time}

\begin{table}[]
{\tiny
\centering
\begin{tabular}{||l|l|l|l|l|l|l|l|l|l|l|l|l|l|l|l|l|l|}
\hline
\multicolumn{18}{|l|}{Progress} \\ \hline
\multicolumn{9}{|l|}{\multirow{2}{*}{Ta}} & \multicolumn{9}{l|}{Ses} \\ \cline{10-18} 
\multicolumn{9}{|l|}{}& H & B & A & H & B & A & H & B & A \\ \hline
\multirow{2}{*}{\begin{tabular}[c]{@{}l@{}} 14\end{tabular}} & \multicolumn{8}{l|}{884} &   &   & \cellcolor{black!15}  &   &   &   &   &   &   \\ \cline{2-18} 
& \multicolumn{8}{l|}{L} &   &   & \cellcolor{black!15} &   &   &   &   &   &   \\ \hline
\multirow{4}{*}{\begin{tabular}[c]{@{}l@{}} 15\end{tabular}}  & \multicolumn{8}{l|}{666} &   &   &   & \cellcolor{black!55}  &   &   &   &   &   \\ \cline{2-18} 
& \multicolumn{8}{l|}{650} &   &   &   & \cellcolor{black!55}  &   &   &   &   &   \\ \cline{2-18} 
& \multicolumn{8}{l|}{0X} &   &   &   & \cellcolor{black!55}  &   &   &   &   &   \\ \cline{2-18} 
& \multicolumn{8}{l|}{11} &   &   &   & \cellcolor{black!55}  &   &   &   &   &   \\ \hline
\end{tabular}}
\end{table}

\end{frame}

\end{document}

As you can see below, it produces a table but not what I want. I want to color the cells and still show the horizontal line between them. When I color two consecutive cells, they will look like a single cell.

EDIT: I added the preamble and the zoomed pdf according to the comments.

Answer 1

The issue you're seeing is to do with the cline command, which is detailed in Section 10 of the colortbl documentation:

If using this package you would probably better using the - rule type in a \hhline argument, rather than \cline.

So, following this guidance, we can load the hhline package and replace

\cline{2-18}

with

\hhline{*{1}{||~}*{17}{|-}}

The output is:

For reference, you might also see \cellcolor overwrites table lines and Cellcolor overwrites partial horizontal lines (\cline)

Here's a complete MWE:

% arara: pdflatex
% !arara: indent: {overwrite: yes}
\documentclass{beamer}
\usepackage{multirow}
\usepackage{xcolor,colortbl}
\usepackage{hhline}

\begin{document}

\begin{frame}
    \frametitle{Time}

    \begin{table}[]
        {\tiny
            \centering
            \begin{tabular}{||*{18}{l|}}
                \hline
                \multicolumn{18}{|l|}{Progress} \\ \hline
                \multicolumn{9}{|l|}{\multirow{2}{*}{Ta}} & \multicolumn{9}{l|}{Ses} \\ \cline{10-18}
                \multicolumn{9}{|l|}{}& H & B & A & H & B & A & H & B & A \\ \hline
                \multirow{2}{*}{\begin{tabular}[c]{@{}l@{}} 14\end{tabular}} & \multicolumn{8}{l|}{884} &   &   & \cellcolor{black!15} &                      &   &   &   &   &   \\ \hhline{*{1}{||~}*{17}{|-}}%\cline{2-18}
                                                                             & \multicolumn{8}{l|}{L}   &   &   & \cellcolor{black!15} &                      &   &   &   &   &   \\ \hline
                \multirow{4}{*}{\begin{tabular}[c]{@{}l@{}} 15\end{tabular}} & \multicolumn{8}{l|}{666} &   &   &                      & \cellcolor{black!55} &   &   &   &   &   \\ \hhline{*{1}{||~}*{17}{|-}}%\cline{2-18}
                                                                             & \multicolumn{8}{l|}{650} &   &   &                      & \cellcolor{black!55} &   &   &   &   &   \\ \hhline{*{1}{||~}*{17}{|-}}%\cline{2-18}
                                                                             & \multicolumn{8}{l|}{0X}  &   &   &                      & \cellcolor{black!55} &   &   &   &   &   \\ \hhline{*{1}{||~}*{17}{|-}}%\cline{2-18}
                                                                             & \multicolumn{8}{l|}{11}  &   &   &                      & \cellcolor{black!55} &   &   &   &   &   \\ \hline
            \end{tabular}}
    \end{table}

\end{frame}

\end{document}