I recently went through my CSS file and switch all my 6-digit hexadecimal codes to simple 3-digit codes (for example, my #FDFEFF got shortened to #FFF). It renders pretty much the exact same color as before, it seems to me that the in between parts are fairly useless and removing them saved me an entire 300 bytes in my CSS file.
Does it matter which version you use? I rarely ever run across websites that use only the 3-digit codes (or I guess I just never run across ones that do). Is it still perfectly valid to use 3-digit codes over 6-digit codes, or are we supposed to use the full 6-digit codes?