# How to place the Greek letters in a good shape around the diagonal line in a Cell (Table)?

I have the following table

\documentclass{article}

\usepackage{lscape}

\usepackage{float}
\usepackage{booktabs}
\usepackage{multirow}

\usepackage{diagbox}

\usepackage[para,online,flushleft]{threeparttable}

\begin{document}

\begin{table}[H!]
\centering
\resizebox{\textwidth}{!}
{
\begin{tabular}{cccccccccccc}\toprule
\diagbox[width=2em]{\raisebox{-1pt}{$\beta$}}{\quad $\alpha$}& 1 & 1.1 & 1.2 & 1.3 & 1.4 & 1.5 & 1.6 & 1.7 & 1.8 & 1.9 & 2\\ \midrule
0 & $0.013$ & $0.013$ & $0.02$ & $0.015$ & $0.015$ & $0.02$ & $0.023$ & $% 0.023$ & $0.024$ & $0.026$ & $0.035$ \\
0.25 & $0.013$ & $0.013$ & $0.02$ & $0.015$ & $0.015$ & $0.02$ & $0.023$ & $% 0.023$ & $0.024$ & $0.025$ & $0.035$ \\
0.5 & $0.013$ & $0.013$ & $0.015$ & $0.015$ & $0.015$ & $0.02$ & $0.023$ & $% 0.023$ & $0.024$ & $0.025$ & $0.035$ \\
0.75 & $0.013$ & $0.013$ & $0.015$ & $0.015$ & $0.015$ & $0.02$ & $0.023$ & $% 0.023$ & $0.024$ & $0.025$ & $0.035$ \\
1 & $0.013$ & $0.013$ & $0.015$ & $0.015$ & $0.015$ & $0.02$ & $0.023$ & $% 0.023$ & $0.024$ & $0.025$ & $0.035$ \\
\bottomrule
\end{tabular}
}
\caption{All possible values of $F(v)$ for varying $(\alpha ,\beta)$ when $T=400$ for $95\%$ CI}
\label{table:CI95}
\end{table}

\end{document}


I would like to place the alpha and beta correctly on the diagonal line. How may I do so?

I would like to suggest that you not use \diagbox and, moreover, not use \resizebox. Instead, simply reorganize the header material slightly and, importantly, use a tabular* environment, with width set to \textwidth. Aligning the numeric data on the decimal markers wouldn't be a bad idea either.

\documentclass{article}
\usepackage{booktabs,siunitx,caption}
\begin{document}

\begin{table}
\small
\setlength\tabcolsep{0pt} % let 'tabular*' determine whitespace
\begin{tabular*}{\textwidth}{l@{\extracolsep{\fill}}*{11}{S[table-format=1.3]}}
\toprule
& \multicolumn{11}{c}{$\alpha$} \\
\cmidrule{2-12}
$\beta$ & {1} & {1.1} & {1.2} & {1.3} & {1.4} & {1.5} & {1.6} & {1.7} & {1.8} & {1.9} & {2}\\
\midrule
0 & 0.013 & 0.013 & 0.02 & 0.015 & 0.015 & 0.02 & 0.023 & 0.023 & 0.024 & 0.026 & 0.035 \\
0.25 & 0.013 & 0.013 & 0.02 & 0.015 & 0.015 & 0.02 & 0.023 & 0.023 & 0.024 & 0.025 & 0.035 \\
0.5 & 0.013 & 0.013 & 0.015 & 0.015 & 0.015 & 0.02 & 0.023 & 0.023 & 0.024 & 0.025 & 0.035 \\
0.75 & 0.013 & 0.013 & 0.015 & 0.015 & 0.015 & 0.02 & 0.023 & 0.023 & 0.024 & 0.025 & 0.035 \\
1 & 0.013 & 0.013 & 0.015 & 0.015 & 0.015 & 0.02 & 0.023 & 0.023 & 0.024 & 0.025 & 0.035 \\
\bottomrule
\end{tabular*}
\captionsetup{font=small}
\caption{All possible values of $F(v)$ for varying $(\alpha ,\beta)$ when $T=400$ for 95\%~CI}
\label{table:CI95}
\end{table}

\end{document}