How do I equate an existing #rgb hex color notation to #rrggbb hex color notation?

I have an old .css code where most color notations are like #fff or #999 or #ccc or #ffc. They all resemble like coming from the browser safe color era.

Now I want to turn those notations in 256 range per color (but still in hex). For #000 and #fff is easy, but how do I make the ‘conversion’ to #rrggbb in order to keep the same hue on the visual perception ? For example #666 or #ffc.

>Solution :

To convert shorthand hex color codes (like #666, #ffc) to full hex codes (#rrggbb):

1. Shorthand Structure: A shorthand hex code like #666 or #ffc represents the color #666666 or #ffffcc, respectively.
2. Conversion Process: Double each character in the shorthand code:
   • #666 becomes #666666
   • #ffc becomes #ffffcc

This method preserves the color’s visual appearance.