The 216 basic Web page colors displayed prettily

This first table is of fully saturated colours - on the edge of the colour cube, if you would like to imagine it that way.

FFF
FCF   FFC   CFF   FCF
F9F   FCC   FF9   CFC   9FF   CCF   F9F
F6F   F9C   FC9   FF6   CF9   9FC   6FF   9CF   C9F   F6F
F3F   F6C   F99   FC6   FF3   CF6   9F9   6FC   3FF   6CF   99F   C6F   F3F
F0F   F3C   F69   F96   FC3   FF0   CF3   9F6   6F9   3FC   0FF   3CF   69F   96F   C3F   F0F
  F0C   F39   F66   F93   FC0   CF0   9F3   6F6   3F9   0FC   0CF   39F   66F   93F   C0F  
C0C   F09   F36   F63   F90   CC0   9F0   6F3   3F6   0F9   0CC   09F   36F   63F   90F   C0C
  C09   F06   F33   F60   C90   9C0   6F0   3F3   0F6   0C9   09C   06F   33F   60F   90C  
909   C06   F03   F30   C60   990   6C0   3F0   0F3   0C6   099   06C   03F   30F   60C   909
  906   C03   F00   C30   960   690   3C0   0F0   0C3   096   069   03C   00F   30C   609  
606   903   C00   930   660   390   0C0   093   066   039   00C   309   606
  603   900   630   360   090   063   036   009   306  
303   600   330   060   033   006   303
  300   030   003  
000

In this next table, the colours are not saturated.

CCC
C9C   CC9   9CC   C9C
C6C   C99   CC6   9C9   6CC   99C   C6C
C3C   C69   C96   CC3   9C6   6C9   3CC   69C   96C   C3C
  C39   C66   C93   9C3   6C6   3C9   39C   66C   93C  
939   C36   C63   993   6C3   3C6   399   36C   63C   939
  936   C33   963   693   3C3   396   369   33C   639  
636   933   663   393   366   339   636
  633   363   336  
333

In this last, small table, the colours are very gentle, and relatively close to the surrounding grey.

999
969   996   699   969
  966   696   669  
666

To get the correct colour code for any of these colours, double each character and add a # at the front.
Thus, for the box marked "603" the correct colour code is #660033.