\documentclass[12pt]{article}% Jon Slaughter / hv
\usepackage[table]{xcolor}
\definecolor{cLightRed}{rgb}{1,.70,.70}
\definecolor{cLightYellow}{rgb}{.90,.85,.55}
\definecolor{cLightGray}{rgb}{.90,.90,.90}
\definecolor{cMediumGray}{rgb}{.70,.70,.70}
\definecolor{cDarkGray}{rgb}{.50,.60,.70}
\usepackage{array}
\newcommand{\thickc}[1][0.5pt]{\vrule width #1}
\usepackage{booktabs}

\makeatletter
\def\markCell{\@ifnextchar[{\@markCelli}{\@markCellii}}
\def\@markCelli[#1]#2#3{%
  \hspace{0pt}\makebox[0pt][l]{%
  \raisebox{-0.25\height}{\huge\textcolor[#1]{#2}{#3}}}%
}
\def\@markCellii#1#2{%
  \hspace{0pt}\makebox[0pt][l]{%
  \raisebox{-0.25\height}{\huge\textcolor{#1}{#2}}}%
} 
\makeatother

\begin{document}
\begin{center}
\renewcommand{\arraystretch}{1.35}
\begin{tabular}{|l|c|c|m{4cm}|} \bottomrule[2pt]
  \multicolumn{4}{!{\thickc[2pt]}c!{\thickc[2pt]}}{%
     \large \textbf{Boot Loader Header Table}}\\\specialrule{2pt}{0pt}{0pt}
  \multicolumn{4}{!{\thickc[1pt]}>{\columncolor{cLightYellow}}r!{\thickc[1pt]}}{%
     \large Version Independent }\\\specialrule{1pt}{0pt}{0pt}
  \multicolumn{1}{!{\thickc[1pt]}>{\columncolor{cDarkGray}}c|}{Entry}
  & \multicolumn{1}{|>{\columncolor{cDarkGray}}c|}{Location}
  & \multicolumn{1}{|>{\columncolor{cDarkGray}}c|}{Size}
  & \multicolumn{1}{|>{\columncolor{cDarkGray}}c!{\thickc[1pt]}}{Comments} \\\specialrule{1pt}{0pt}{0pt}
%
  \rowcolor{cLightGray} JmpTrap & 0 & Word & 0EBFEh (JMP \$) \\ \hline
  \rowcolor{cMediumGray} MagicNumber & 2 & Word & 0AA55h \\ \hline
  \rowcolor{cLightGray} Name & 4 & 4 Bytes & 'EBLH' \\ \hline
  \rowcolor{cMediumGray} Version & 8 & Word & Version of BLH table \\ \hline
  \rowcolor{cLightGray} Size & 10 & Byte & Size of BLH table \\ \hline
  \rowcolor{cMediumGray}SizeVDT & 11 & Byte & Size of follow version dependent table\\\hline
  \multicolumn{4}{!{\thickc[1pt]}>{\columncolor{cLightYellow}}r!{\thickc[1pt]}}{%
    \large Version 1.x }\\\hline
  \rowcolor{cLightGray} Empty & 0 & 0 & No Data for 1.x\\\specialrule{2pt}{0pt}{0pt}
  \multicolumn{4}{!{\thickc[2pt]}c!{\thickc[2pt]}}{%
    \large \textbf{End of Boot Loader Header Table}}\\[-2pt]
  \bottomrule[2pt]
\end{tabular}
\end{center}

\end{document}