Web safe colors


I dont know if this belongs here on CSS, on HTML or miscellaneous, but I posted it here on CSS.

I remember back in time we had the standard called web safe colors. Reason I ask is because

I am not sure if this is something that is applicable today, but how important is it with websafe colors today?
The best in my opinion is hex string like #rgb or #rrggbb.
You can read about colors here: https://quickref.me/css#css-colors
I can suggest to you to read about css functions like rgb() and hsl here: https://www.w3schools.com/cssref/css_functions.asp