Why does CSS3 duplicate

  1. #00ffff = 0,255,255 and

  2. #FF00FF = (255, 0, 255), spotted by this user?

This duplication confuses, as each is listed separately on the aforementioned CSS3 link.

  • 20
    Typically things like this are done simply to preserve backward compatibility. Nothing more and nothing less. The reality is the is non-issue since most developers nowadays don’t use word/name-based color designations anyway. It’s all either a hex triplet or an RGB value of some kind to get colors that are more accurate to a designers vision. And even if there were no deep design concerns, I personally would just code a color as #00ffff or #ff00ff to be explicit about what color I want rendered. Heck, I don’t recall ever using name-based colors since the first website I code back in 1995. Jan 24, 2019 at 3:10
  • 1
    @AndrewT. Considering the Greek proposal has already failed, been closed and subsequently deleted, along with all the other borderline worthless language/country proposals this user advertises in his profile, we'll have to agree to disagree on just how "okay" advertising is in a username. In this case it is not even an advert, it is more an advert advertising a failed advert.
    – Mokubai
    Jan 24, 2019 at 17:12
  • 4
    @JakeGould Ah backwards compatibility. The reason why darkgray is lighter than gray.
    – Bakuriu
    Jan 24, 2019 at 19:33

1 Answer 1


There are a few clashing/duplicate colors listed in CSS3 because the current web colors list maintained by W3C was descended from the X11 color names file.

The X Window System contained a text file that had RGB values that mapped to certain colors. This text file was shipped with all X11 installations.

Mosaic and Netscape Navigator both used the X11 color names as the basis of their colors.

Once the HTML color list was defined, instead of deprecating the duplicate and clashing colors, they simply adopted them into the list - presumably to prevent breaking older websites/browsers that used X11 colors and because X11 had defined them first.

That being said, if you use a clashing color name on a site today, it would display the W3C color instead of the X11 color.

  • 13
    Folks, please do not submit or approve proposed edits that include switching words between USA and UK spelling variations. In this particular scenario, it wasn't appropriate to change "colors" to "colours."
    – Run5k
    Jan 24, 2019 at 13:47
  • @DrZoo FYI you still earn rep from suggested edits even after 2k rep overall; the only limit is +1000 rep from suggested edits. It's just that in most cases you see it end at 2k because you can no longer suggest edits, and suggested edits don't take that long to get approved.
    – TylerH
    Jan 24, 2019 at 16:24

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