CurrentColor in CSS
If you've ever used something like LESS or SASS you know what a variable is in CSS. There is also a working draft for native CSS variables but there is something in CSS right now that resembles some variable behavior. Not an actual variable, but interesting nonetheless.
Meet currentColor. Like the description says on the w3 wiki, its value is whatever the
color is set to. So how does that work? Lets look at some examples.
Sample one shows
currentColor in its simplest form. It takes on the color Red which controls the border color.
Sample two is a tiny bit more complex. Here you can see the
currentColor cascading down (Blue in this case) which sets a blue box-shadow on the
Sample three is where we see that
color to Green and using
currentColor to set the border color. Then we set the
color to Yellow to change the background color. You can see it go wrong immediately, the text and border isn't green! This is because you can't re-assign
currentColor. It can only be set once for every style and takes the value of the last time the
color was set so in the sample it turns everything Yellow. When
color is reset,
currentColor is also reset as you can see, but cannot be set multiple times for the same set of styles. The inner div has black text and box-shadow because this has a different scope.
So in short, kind of like a variable but not actually a variable. I don't see currentColor used very often in projects I get to work on, though its pretty safe to use (unless you support IE8). It can be used to save yourself some problems in dealing with consistent colors but you might be better off using LESS or SASS if you want to use variables :-)