CSS colors extractor

== Why ? ==

I needed a tool that can quickly and reliably extract all CSS color mentioned in HTML/CSS (or whatever source language really) code, then index and report them in a clear and easy to read fashion. The end goal was to upgrade some old website base files to leverage CSS variables for color palette management.

Surprizingly enough, I searched for some online tool which could do the job but none proved able to reliably do it. Some did a better job than others but all of them managed to miss several colors, so I thought building yet another _actually reliable and maintained_ tool for this task might be of use in this day and age.

== Features ==

  * Supports 150 CSS named colors (including rebeccapurple ans transparent) out of the box. (ref : https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/Values/named-color ). currentColor support is of little interest as it is more a dynamic variable than a color constant, but can be optionally enabled and indexed if so desired.
  * Optionally supports CSS system colors as well as deprecated system colors (ref : https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/Values/system-color ).
  * Relative colors [from <color> <modifiers>] (ref: https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Colors/Using_relative_colors ) are not supported (yet ?), as it is quite a rabbit hole to dig into, however adding some level of support for them would be a great addition in the future.
  * Fully supports alpha channel/transparency
  * Supports hex color formats #rgb #rrggbb #rgba #rrggbbaa
  * Supports (absolute) rgb functional notation, rgb() & rgba(), with or without alpha, whether comma-separated (legacy syntax) or space-separated with a / denoting alpha value (modern syntax) (ref: https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/Values/color_value/rgb )

== Usage ==