# Increase row height and center, but only the first row

I have a table, built using the tabu package.

My code currently looks like below. The \\[5ex] does increase the row height, but the contents of the third cell is aligned top instead of middle (notice the X[c,m] definition). The \arraystretch changes the height of all the rows, but I only want to increase the height of only the first one.

\documentclass[]{article}

\usepackage{tabu}

\begin{document}

\begin{table}[h!]
\begin{center}
\begin{tabu} to 0.5\linewidth {| X[c,m] | X[c,m] | X[c,m] |}
\hline
\textbf{First column} & \textbf{Second Column} & \textbf{Third Column} \\[5ex] \hline
\hline

1 & 0x1 & 01 \\ \hline
2 & 0x2 & 02 \\ \hline
3 & 0x3 & 03 \\ \hline
4 & 0x4 & 04 \\ \hline
5 & 0x5 & 05 \\ \hline
6 & 0x6 & 06 \\ \hline
7 & 0x7 & 07 \\ \hline
8 & 0x8 & 010 \\ \hline
9 & 0x9 & 011 \\ \hline
10 & 0xa & 012 \\ \hline

\end{tabu}
\end{center}

\caption{Example of another short table, but smaller and centered.}
\end{table}

\end{document}


I'll admit it is not pretty, but I placed top rules \tr before each 1st-row column and a bottom rule \br after each 1st-row column.

Trying to accomplish it with a single rule caused inter-word vertical space to appear. And trying to do it in one rather than three columns caused a disparity between the column positioning.

\documentclass[]{article}

\usepackage{tabu}
\newcommand\tr{\rule{0pt}{4.5ex}}
\newcommand\br{\rule[-3ex]{0pt}{3ex}}
\begin{document}

\begin{table}[h!]
\begin{center}
\begin{tabu} to 0.5\linewidth {| X[c,m] | X[c,m] | X[c,m] |}
\hline
\tr\textbf{First column}\br & \tr\textbf{Second Column}\br &
\tr\textbf{Third Column}\br \\ \hline
\hline

1 & 0x1 & 01 \\ \hline
2 & 0x2 & 02 \\ \hline
3 & 0x3 & 03 \\ \hline
4 & 0x4 & 04 \\ \hline
5 & 0x5 & 05 \\ \hline
6 & 0x6 & 06 \\ \hline
7 & 0x7 & 07 \\ \hline
8 & 0x8 & 010 \\ \hline
9 & 0x9 & 011 \\ \hline
10 & 0xa & 012 \\ \hline

\end{tabu}
\end{center}

\caption{Example of another short table, but smaller and centered.}
\end{table}

\end{document}