Your comments

i'm on Windows 7 64bits. I install it via ctrl+alt+P command panel (install package), then LiveCSS. I had another package i tried for CSS too, but removed it.

Now i can't remove the package because it instant crashes since i put #fff directly ... i guess the package tries to make something with the color (highlighting or whatever) but it crashes :(

For some reasons, it makes the software crash ! when i finish writting a color (#fff, for example), it crashes right before the color is made... (so at #ff)

Oh ! i just noticed ! This would be great too !

Oh, i installed it and it's approximatly what i was looking for. But yeah rgba is missing, but it's a good start. Thanks for this tip :)