[HugoGiraudel]

Actually I am thinking of changing this. Someone brought the issue on GitHub: https://github.com/HugoGiraudel/sass-guidelines/issues/32. It is currently being discussed.

[wldcordeiro]

In a similar vein why do you prefer hex colors in shortened lowercase format? I've been partial to uppercase long form.

[pc86]

This is not in a similar vein. Leading zero's for values less than 1 is the correct way to write values less than 1.

3-character or 6-character hex values is only a matter of optimization (fewer characters, which the compiler should be able to handle), and consistency (having both the 3- and 6-character versions in the same file or definition). Case is personal preference and nothing more.