'Internal borders' in table cells

I am looking to add borders to some cells in a table, such that the borders surround the contents and there is a space between each cell. The best image I could find that shows sort of what I want to achieve is this:

This is possible in HTML via the cellspacing setting in tables. How can I achieve the same in LaTeX? I would only want a few of the table cells to have this internal border, not all of them.

The closest I have come is by using fbox, but I couldn't get them to extend all the way to the edges of the table cells.

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have a look at Example of fancy table using TikZ package – cmhughes Apr 13 '13 at 22:33

For simple tables an easy solution is the hhline package, but I think that is not a good solution for complex tables with \multiwrow and \multicolumn cells, as showed in your question.

In this MWE are showed both problems:

\documentclass{article}
\usepackage[table]{xcolor}
\usepackage{hhline}
\usepackage{multirow}
\begin{document}
\arrayrulecolor{black}
\doublerulesepcolor{gray!40}
\begin{tabular}{||>{\columncolor[gray]{0.9}\bfseries}c||c||c||c||c||}
\hhline{|t:=:t:=:t:=:t:=:t:=:t|}
\rowcolor{red!30}
\multirow{2}{*}{alfa} & \bfseries beta & \multicolumn{2}{|c||}{\bfseries beta} & \bfseries alfa \\
\hhline{||~|:=::=::=::=:|}
& beta & alfa & beta & alfa \\
\hhline{|:=::=::=::=::=:|}
alfa & beta & alfa & beta & alfa \\
\hhline{|:=::=::=::=::=:|}
alfa & beta & alfa & beta & alfa \\
\hhline{|:=::=::=::=::=:|}
\rowcolor{green!30} gamma & delta & gamma & delta & gamma \\
\hhline{|b:=:b:=:b:=:b:=:b:=:b|}
\end{tabular}
\end{document}

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You can put multirow in the second row:  & \bfseries beta & \multicolumn{2}{|c||}{\bfseries beta} & \bfseries alfa \\hhline{||~|:=::=::=::=:|} \multirow{-2}{*}{alfa}& beta & alfa & beta & alfa \\  so that the text doesn't get clipped. – Harish Kumar Apr 10 '13 at 23:52
@HarishKumar, yes, much better in this way. But the multirow cell still have 3 colors. Too much for my taste! – Fran Apr 11 '13 at 0:36