I have been playing around with tikz-cd for quite a while and I love it, except when it comes to 3d-cubic diagrams. I have not found a viable solution so far and all the solutions out there seem to have an issue. The one that came closest to solving my problem was this one :
\documentclass{article}
\usepackage{tikz-cd}
\begin{document}
$$
\begin{tikzcd}
S'Sc \ar{rr}{} \ar{rd}{} \ar{dd}{} & & T'Sc \ar{rd}{} \ar{dd}{} & \\
& S'Sc' \ar[crossing over]{rr}{} & & T'Sc \ar{dd}{} \\
S'Tc \ar{rr}{} \ar{rd}{} & & T'Tc \ar{rd}{} & \\
& S'Tc' \ar{rr}{} \ar[<-,crossing over]{uu}{} & & T'Tc
\end{tikzcd}
$$
\end{document}
but in the output, the arrow shown by \ar[<-,crossing over] has a smaller arrow tip than my other arrows; this issue seems to be caused by <- (the point is to reverse its direction).
What is the issue with the commands -> and <- which makes the arrow tip they generate smaller than the other ones?
tikz-cdto version 0.9. This has been fixed already. Do you have the same issue when using thefrom=uusyntax as I do in my cube-answer here: http://tex.stackexchange.com/a/234151 – LaRiFaRi Jan 29 '16 at 09:28\[ … \]preferable to$$? about your usage of$$. – egreg Jan 29 '16 at 10:40