How can I align the small, large and user columns under every multicolumn. Alignment gets lost when using multicolumn. Code below:
\begin{table}[]
\centering
\resizebox{\columnwidth}{!}{
\begin{tabular}{l|c|c|c|c|cccccccccccccccccccccccc}
\toprule
\multirow{3}{*}{\color{red}{\textbf{SAD}}} & \multicolumn{4}{c}{} & \multicolumn{3}{c}{\textbf{Troll}} & \multicolumn{3}{c}{\textbf{Doll}} & \multicolumn{3}{c}{\textbf{Donkey}} & \multicolumn{3}{c}{\textbf{Elephant}} & \multicolumn{3}{c}{\textbf{Plant}} & \multicolumn{3}{c}{\textbf{Pineapple}} & \multicolumn{3}{c}{\textbf{Plastic bag}} & \multicolumn{3}{c}{\textbf{Net}} \\
& overall & avg. small & avg. large & avg. medium & \multicolumn{3}{c}{(Strongly Transparent)} & \multicolumn{3}{c}{(Strongly Transparent)} & \multicolumn{3}{c}{(Medium Transparent)} & \multicolumn{3}{c}{(Medium Transparent)} & \multicolumn{3}{c}{(Little Transparent)} & \multicolumn{3}{c}{(Little Transparent)} & \multicolumn{3}{c}{(Highly Transparent)} & \multicolumn{3}{c}{(Highly Transparent)} \\
& rank & rank & rank & rank & small & large & user & small & large & user & small & large & user & small & large & user & small & large & user & small & large & user & small & large & user & small & large & user \\
\rowcolor{blue!10}
GAN & $1.0_{\color{blue}1}$ & $1.0_{\color{blue}1}$ & $1.0_{\color{blue}1}$ & $1.0_{\color{blue}1}$ & $1.0_{\color{blue}1}$ & $1.0_{\color{blue}1}$ & $1.0_{\color{blue}1}$ & $1.0_{\color{blue}1}$ & $1.0_{\color{blue}1}$ & $1.0_{\color{blue}1}$ & $1.0_{\color{blue}1}$ & $1.0_{\color{blue}1}$ & $1.0_{\color{blue}1}$ & $1.0_{\color{blue}1}$ & $1.0_{\color{blue}1}$ & $1.0_{\color{blue}1}$ & $1.0_{\color{blue}1}$ & $1.0_{\color{blue}1}$ & $1.0_{\color{blue}1}$ & $1.0_{\color{blue}1}$ & $1.0_{\color{blue}1}$ & $1.0_{\color{blue}1}$ & $1.0_{\color{blue}1}$ & $1.0_{\color{blue}1}$ & $1.0_{\color{blue}1}$ & $1.0_{\color{blue}1}$ & $1.0_{\color{blue}1}$ & $1.0_{\color{blue}1}$ \\
\bottomrule
\end{tabular}
}
\label{tab:my_label}
\end{table}
