Ytdyklly

Using the code given below, I am getting a black line over the word "Methods" due to hhline. How shall I remove this black line or make it of same color as the background color so that it is not visible?

documentclass{article}

  usepackage{hhline}

 usepackage[table]{xcolor}

   usepackage{array}

 usepackage{hhline}

  usepackage{multirow}

  definecolor{babyblue}{rgb}{0.54, 0.81, 0.94}

   definecolor{aliceblue}{rgb}{0.94, 0.97, 1.0}

    begin{document}

    begin{table}

    centering

    setlengtharrayrulewidth{1.3pt}

        footnotesizesetlength{tabcolsep}{2.7 pt}

    renewcommand{arraystretch}{1.4}

    begin{tabular}{|c|c|c|c|c|c|c|}

        hline

        cellcolor{aliceblue}  & multicolumn{2}{c|}{cellcolor{babyblue}ISE} & multicolumn{2}{c|}{cellcolor{babyblue}IAE} & multicolumn{2}{c|}{cellcolor{babyblue}ITAE} \ hhline{-|-|-|-|-|-|-|} cline{2-7} 

            multirow{-2}{*}{cellcolor{aliceblue} Methods}

        & cellcolor{aliceblue}-20%       & cellcolor{aliceblue}+20%     & cellcolor{aliceblue}-20%       & cellcolor{aliceblue}+20%      & cellcolor{aliceblue}-20%       & cellcolor{aliceblue}+20%       \ hhline{-|*6-}

        rowcolor{babyblue}ABC                                                           & 0.5645      & 0.63     & 1.8       & 1.8      & 6.1       & 6.6       \ hhline{-|*6-}

        rowcolor{aliceblue}XYZ                                                            & 2.1       & 2.3      & 0.881       & 9.82      & 9.2       & 28.9       \ hhline{-|*6-}

        rowcolor{babyblue}MNO                                                                & 0.68      & 0.97     & 1.62       & 1.61      & 8.9       & 8.2       \ hhline{-|*6-}

        rowcolor{aliceblue} PQR                                                                 & 0.65       & 0.753     & 2.064       & 2.231      & 28.04       & 28.56       \ hhline{-|*6-}

    end{tabular}

    end{table}

   end{document}

You need to change your used command hhline{-|-|-|-|-|-|-|} to hhline{|~|-|-|-|-|-|-|} (see the ~ at the first position marking there should be no line).

So the following MWE

documentclass{article}



usepackage{hhline}

usepackage[table]{xcolor}

usepackage{array}

usepackage{multirow}



definecolor{babyblue}{rgb}{0.54, 0.81, 0.94}

definecolor{aliceblue}{rgb}{0.94, 0.97, 1.0}





begin{document}



begin{table}

  centering

  setlengtharrayrulewidth{1.3pt}

  footnotesizesetlength{tabcolsep}{2.7 pt}

  renewcommand{arraystretch}{1.4}

  begin{tabular}{|c|c|c|c|c|c|c|}

    hline

    cellcolor{aliceblue}  & multicolumn{2}{c|}{cellcolor{babyblue}ISE} & multicolumn{2}{c|}{cellcolor{babyblue}IAE} & multicolumn{2}{c|}{cellcolor{babyblue}ITAE} \ 

   hhline{|~|-|-|-|-|-|-|} % <==========================================

    multirow{-2}{*}{cellcolor{aliceblue}Methods}

        & cellcolor{aliceblue}-20%       & cellcolor{aliceblue}+20%     & cellcolor{aliceblue}-20%        & cellcolor{aliceblue}+20%      & cellcolor{aliceblue}-20%       & cellcolor{aliceblue}+20%        \ hhline{-|*6-}

    rowcolor{babyblue}ABC                                                           & 0.5645      & 0.63     & 1.8       & 1.8      & 6.1       & 6.6       \ hhline{-|*6-}

    rowcolor{aliceblue}XYZ                                                            & 2.1       & 2.3      & 0.881       & 9.82      & 9.2       & 28.9       \ hhline{-|*6-}

    rowcolor{babyblue}MNO                                                                & 0.68      & 0.97     & 1.62       & 1.61      & 8.9       & 8.2       \ hhline{-|*6-}

    rowcolor{aliceblue} PQR                                                                 & 0.65       & 0.753     & 2.064       & 2.231      & 28.04       & 28.56       \ hhline{-|*6-}

  end{tabular}

end{table}

end{document}

results in the following table:

Because you do not want to get rid of the lines I deleted the second table.

To get rid of the underlaying white line under text "Method" you need to change the command hhline{|~|-|-|-|-|-|-|} to

hhline{|>{arrayrulecolor{aliceblue}}->{arrayrulecolor{black}}|-|-|-|-|-|-|}

Please see that this code prints the first part of line (marked with - again; ~ adds the white line!) and colored it in the same color the background has.

With the following MWE

documentclass{article}



usepackage{hhline}

usepackage[table]{xcolor}

usepackage{array}

usepackage{multirow}

usepackage{booktabs}



definecolor{babyblue}{rgb}{0.54, 0.81, 0.94}

definecolor{aliceblue}{rgb}{0.94, 0.97, 1.0}





begin{document}



begin{table}[ht]

  centering

  setlengtharrayrulewidth{1.3pt}

  footnotesizesetlength{tabcolsep}{2.7 pt}

  renewcommand{arraystretch}{1.4}

  begin{tabular}{|c|c|c|c|c|c|c|}

    hline

    cellcolor{aliceblue}  & multicolumn{2}{c|}{cellcolor{babyblue}ISE} & multicolumn{2}{c|}{cellcolor{babyblue}IAE} & multicolumn{2}{c|}{cellcolor{babyblue}ITAE} \ 

   hhline{|>{arrayrulecolor{aliceblue}}->{arrayrulecolor{black}}|-|-|-|-|-|-|} % <==========================================

    multirow{-2}{*}{cellcolor{aliceblue}Methods}

        & cellcolor{aliceblue}-20%       & cellcolor{aliceblue}+20%     & cellcolor{aliceblue}-20%        & cellcolor{aliceblue}+20%      & cellcolor{aliceblue}-20%       & cellcolor{aliceblue}+20%        \ hhline{-|*6-}

    rowcolor{babyblue}ABC                                                           & 0.5645      & 0.63     & 1.8       & 1.8      & 6.1       & 6.6       \ hhline{-|*6-}

    rowcolor{aliceblue}XYZ                                                            & 2.1       & 2.3      & 0.881       & 9.82      & 9.2       & 28.9       \ hhline{-|*6-}

    rowcolor{babyblue}MNO                                                                & 0.68      & 0.97     & 1.62       & 1.61      & 8.9       & 8.2       \ hhline{-|*6-}

    rowcolor{aliceblue} PQR                                                                 & 0.65       & 0.753     & 2.064       & 2.231      & 28.04       & 28.56       \ hhline{-|*6-}

  end{tabular}

end{table}



end{document}

you get the result:

i would redesign your table as follows:

documentclass{article}

usepackage{siunitx}

usepackage[table]{xcolor}

definecolor{babyblue}{rgb}{0.54, 0.81, 0.94}

definecolor{aliceblue}{rgb}{0.94, 0.97, 1.0}

usepackage{booktabs, multirow}

newcommandmcc[1]{multicolumn{2}{c}{#1}}



begin{document}



begin{table}[htb]

  centering

  renewcommandarraystretch{1.2}

  rowcolors{2}{white}{aliceblue}

  begin{tabular}{c *{6}{S} }

    toprule

        & mcc{ISE} & mcc{IAE} & mcc{ITAE}                \

    cmidrule(lr){2-3}cmidrule(lr){4-5}cmidrule(lr){6-7}

multirow{-2.3}{*}{Methods}

        & {$-20%$} & {$+20%$}

                    & {$-20%$} & {$+20%$}

                                & {$$-20%$} & {$+20%$}         \

    hline

ABC     & 0.5645    & 0.63  & 1.8   & 1.8   & 6.1   &  6.6  \

XYZ     & 2.1       & 2.3   & 0.881 & 9.82  & 9.2   & 28.9  \

MNO     & 0.68      & 0.97  & 1.62  & 1.61  & 8.9   &  8.2  \

PQR     & 0.65      & 0.753 & 2.064 & 2.231 & 28.04 & 28.56 \

    bottomrule

  end{tabular}

end{table}

end{document}

Here is a solution for the white line in the multirow. intead of using hhline{~|-|-|-|-|-|-|}, I use a full width hhline , but make the first segment coloured with the background colour of the multirow.

I also took the liberty to simplify your code, and use the AliceBlue colour from svgnames, as it doesn't seem different from your aliceblue.

documentclass{article}



usepackage{hhline}

usepackage[table, svgnames]{xcolor}

usepackage{array}

usepackage{multirow}

usepackage{booktabs}



definecolor{babyblue}{rgb}{0.54, 0.81, 0.94}



begin{document}



begin{table}[ht]

  centering

  setlengtharrayrulewidth{1.3pt}

  footnotesizesetlength{tabcolsep}{2.7 pt}

  renewcommand{arraystretch}{1.4}

  begin{tabular}{|c|c|c|c|c|c|c|}

    hline

    cellcolor{aliceblue} & multicolumn{2}{c|}{cellcolor{babyblue}ISE} & multicolumn{2}{c|}{cellcolor{babyblue}IAE} & multicolumn{2}{c|}{cellcolor{babyblue}ITAE} \

   hhline{|>{arrayrulecolor{AliceBlue}}->{arrayrulecolor{black}}|*6{-}} % <==========================================

rowcolor{AliceBlue} multirow{-2}{*}{Methods}

        &$ - $20% & +20% & $ - $20% & +20% & $ - $20% & +20% \ hhline{-|*6-}

    rowcolor{babyblue}ABC & 0.5645 & 0.63 & 1.8 & 1.8 & 6.1 & 6.6 \ hhline{-|*6-}

    rowcolor{AliceBlue}XYZ & 2.1 & 2.3 & 0.881 & 9.82 & 9.2 & 28.9 \ hhline{-|*6-}

    rowcolor{babyblue}MNO & 0.68 & 0.97 & 1.62 & 1.61 & 8.9 & 8.2 \ hhline{-|*6-}

    rowcolor{AliceBlue} PQR & 0.65 & 0.753 & 2.064 & 2.231 & 28.04 & 28.56 \ hhline{-|*6-}

  end{tabular}

end{table}



end{document}