Multiple \arrayrulecolor per line with booktabs - latex

Question

Taking this to tex.stackexhange.
The problem
Let's say I want to have more than rules in two different colors in the same row ... how can I make it work?
Here is a minimal example:
\documentclass{article}
\usepackage{colortbl}
\usepackage{booktabs}
\begin{document}
\begin{table}[ht]
\begin{tabular}{llll}
\toprule
A & B & alpha & beta\\
\arrayrulecolor{black} \cmidrule[1pt](l){1-1} \arrayrulecolor{red} \cmidrule[1pt](r){2-2} \arrayrulecolor{black} \cmidrule[1pt](l){3-3} \arrayrulecolor{black} \cmidrule[1pt](r){4-4}
1 & 5 & 10 & 100\\
2 & 6 & 11 & 101\\
2 & 7 & 12 & 102\\
3 & 8 & 13 & 103\\
\bottomrule
\end{tabular}
\end{table}
\end{document}
What happens is that with each call of \arrayrulecolor{}, the corresponding cmidrule is moved down. Is there a solution to this?
The problem with the earlier solution
The solution mentioned in the comments has some trouble when you have different widths in one row. Consider this example:
\documentclass{article}
\usepackage{colortbl}
\usepackage{booktabs}
\newcommand{\corcmidrule}[1][2pt]{% \corcmidrule[<len>]
\\[\dimexpr-\normalbaselineskip-\belowrulesep-\aboverulesep-#1\relax]%
}
\begin{document}
\begin{table}[ht]
\begin{tabular}{llll}
\toprule
A & B & alpha & beta\\
\arrayrulecolor{black}\cmidrule[1pt](l){1-1}
\corcmidrule[2pt]\arrayrulecolor{black}\cmidrule[2pt](r){2-2}
\corcmidrule[5pt]\arrayrulecolor{black}\cmidrule[5pt](l){3-3}
\corcmidrule[1pt]\arrayrulecolor{black}\cmidrule[1pt](r){4-4}
1 & 5 & 10 & 100\\
2 & 6 & 11 & 101\\
2 & 7 & 12 & 102\\
3 & 8 & 13 & 103\\
\bottomrule
\end{tabular}
\end{table}
\end{document}
What's wrong with this?
Consider what it looks like without the macro:
\documentclass{article}
\usepackage{colortbl}
\usepackage{booktabs}
\newcommand{\corcmidrule}[1][2pt]{% \corcmidrule[<len>]
\\[\dimexpr-\normalbaselineskip-\belowrulesep-\aboverulesep-#1\relax]%
}
\begin{document}
\begin{table}[ht]
\begin{tabular}{llll}
\toprule
A & B & alpha & beta\\
\arrayrulecolor{black}\cmidrule[1pt](l){1-1}
\cmidrule[2pt](r){2-2}
\cmidrule[5pt](l){3-3}
\cmidrule[1pt](r){4-4}
1 & 5 & 10 & 100\\
2 & 6 & 11 & 101\\
2 & 7 & 12 & 102\\
3 & 8 & 13 & 103\\
\bottomrule
\end{tabular}
\end{table}
\end{document}
The macro might need a modification.