[$40] Elements' colors depending if background is dark/light

[danimesq]

I'm planning to change the CSS of sidebar elements, but its a problem. I want to change it to white, but for when the background is white? Can you do a system to know the type (darker/whiter) of background?
I think it can help: http://stackoverflow.com/questions/3942878/how-to-decide-font-color-in-white-or-black-depending-on-background-color
(Maybe without the need to use a jquery plugin).

[danimesq]

I preffer the idea of change the font/elements color dynamically, by detecting if background is darker/whiter. Or we can simple use full-white cards (like in the profile) instead of transparent-bg elements.
Regarding the black fonts that don't have background? It can have a black text-shadow.
Just ideas for possibilities, but I think detect background type (darker/whiter) is better, but is the harder way.
I will like so much the profile covers feature, but now my focus is the current background system.