With Dante's recent work on Math [1], now its "color" attribute support all HTML/CSS color names, as well as RGB/hexdecimal codes. The UI also changed, old "cyan/magenta" color names are changed to "aqua/fuchsia" in UI ("cyan/magenta" are still supported as commands). Also a selected few newly supported color names are added to UI, as well as UI for RGB/RGBA/hex codes. See [2] for a screenshot. The documentation for this feature, unfortunately, are out of date now. The help page [3] says "Then enter the color name (black, white, cyan, magenta, red, blue, green, or yellow)". And while the Math Guide book [4] is up-to-date for 7.0 UI, it still needs update for version 7.1, and maybe needs mention of the available colors not presented by UI as well. 1. For example, https://git.libreoffice.org/core/+/f3b52717e85621d3b4ee1c6d69700e2a0cca8efc and https://git.libreoffice.org/core/+/0643dab6819bdf248321d27f6b58a2cce125e51c 2. https://wiki.documentfoundation.org/File:Math_new_color_on_Element_pane_7.1.jpg 3. https://help.libreoffice.org/latest/en-US/text/smath/01/03091506.html 4. Math Guide 7.0, PDF version, page 33 and pages 69-70
Please remember that RGBA will be displayed as RGB. The renderer needs some tweaks for it to work. That is why is hidden in UI. It has been unlocked to avoid unwanted syntax errors. About the supported colors: https://developer.mozilla.org/en-US/docs/Web/CSS/color_value
Proposed patch is available for review: https://gerrit.libreoffice.org/c/help/+/128240
Rafael Lima committed a patch related to this issue. It has been pushed to "master": https://git.libreoffice.org/help/commit/d29732c1b544fa75cb12a30c8feff3109dddc1f8 tdf#138418 Document color command in Math