Slap a # on it and be done. (#8B4513)

And the closest three digit code is easily done by removing the second character in the pair.

So
8B would be 8
45 would be 4
13 would be 1

But this will result in #884411 instead of #8B4513.

8b is 139

It’s not special in any way, it’s just css and it can take whatever the css standard does.
So yes, it will take all the different options I wrote in my answer.

The three digit HEX (#FFF) is just a shorter (and less exact) version of the six digit HEX, like this

#FFF is the same as #FFFFFF
#330 is the same as #333300

But you can’t get exact colors, you can only get a rough version of the colors, the 3 digit HEX is limited in that regard.

But the calendar ext 2 supports only 3 digits

.CX2 .AbfallRest {
  background-color:#330;
  color:#FFF;
 }

Any other Idea?
Thanks

go to : https://rgbcolorcode.com/

There you can pick the color you want and then you use the codes to the right

instead of using the color names

color: red

You can use Hexadecimal

color: #FF0000

Or RGB

color: rgb(255,0,0)

or RGBA (if you want the text to be translucent)

color: rgba(255,0,0,0.8)

(you can use many more, but these will do you just fine)