\documentclass{article}
\usepackage{boldline}
\usepackage{colortbl}

\begin{document}


\begin{tabular}{l l l}
\hlineB{2.7}
\rowcolor[gray]{0.7}
First       & Second      & Third       \\ \hline
A A A A A A & B B B B B B & C C C C C C \\ \hline
D D D D D D & E E E E E E & F F F F F F \\
\hlineB{2.7}
\end{tabular}

\vspace{1cm}

\begin{tabular}{V{2.7}c|c|c V{2.7}}
\hlineB{2.7}
First       & Second      & Third       \\ \hline
A A A A A A & B B B B B B & C C C C C C \\ \hline
D D D D D D & E E E E E E & F F F F F F \\
\hlineB{2.7}
\end{tabular}

\end{document}