After studying the scss source files of bootstrap and also some online resources, I ended up that defining the following SASS mixins would solve my problem:
@import "bootstrap";
.btn-ffa300 {
@include button-variant(#ffa300, darken(#ffa300, 5%));
}
.btn-ffd700 {
@include button-variant(#ffd700, darken(#ffd700, 5%));
}
.btn-97d700 {
@include button-variant(#97d700, darken(#97d700, 5%));
}
.btn-012169 {
@include button-variant(#012169, darken(#012169, 5%));
}
.btn-001489 {
@include button-variant(#001489, darken(#001489, 5%));
}
.btn-ff8200 {
@include button-variant(#ff8200, darken(#ff8200, 5%));
}
.btn-c4d600 {
@include button-variant(#c4d600, darken(#c4d600, 5%));
}
.btn-84bd00 {
@include button-variant(#84bd00, darken(#84bd00, 5%));
}
.btn-0033a0 {
@include button-variant(#0033a0, darken(#0033a0, 5%));
}
.btn-c8c9c7 {
@include button-variant(#c8c9c7, darken(#c8c9c7, 5%));
}
.btn-ff6900 {
@include button-variant(#ff6900, darken(#ff6900, 5%));
}
.btn-78d64b {
@include button-variant(#78d64b, darken(#78d64b, 5%));
}
.btn-009ca6 {
@include button-variant(#009ca6, darken(#009ca6, 5%));
}
.btn-002d72 {
@include button-variant(#002d72, darken(#002d72, 5%));
}
.btn-7c878e {
@include button-variant(#7c878e, darken(#7c878e, 5%));
}
.btn-ff6a13 {
@include button-variant(#ff6a13, darken(#ff6a13, 5%));
}
.btn-ef3340 {
@include button-variant(#ef3340, darken(#ef3340, 5%));
}
.btn-69b3e7 {
@include button-variant(#69b3e7, darken(#69b3e7, 5%));
}
.btn-002f6c {
@include button-variant(#002f6c, darken(#002f6c, 5%));
}
.btn-63666a {
@include button-variant(#63666a, darken(#63666a, 5%));
}
.btn-fe5000 {
@include button-variant(#fe5000, darken(#fe5000, 5%));
}
.btn-c8102e {
@include button-variant(#c8102e, darken(#c8102e, 5%));
}
.btn-003da5 {
@include button-variant(#003da5, darken(#003da5, 5%));
}
.btn-002855 {
@include button-variant(#002855, darken(#002855, 5%));
}
.btn-4f2c1d {
@include button-variant(#4f2c1d, darken(#4f2c1d, 5%));
}
I even confirmed that it's working by rewriting my previous fiddle, and indeed the result ended up EXACTLY as I wanted it to be (https://www.codeply.com/go/uYPxiuNkbu).
Codeply is also "kind enough" to provide in the appropriate tab the compiled css of the sass code used in the fiddle...
But that's an indirect way of preprocessing the sass code... What would a proper way be? Isn't there some sort of online CSS preprocessor? Ie, I read that (https://themestr.app/customize) can be used to customize bootstrap code and then all customizations end up in a compiles custom.css file... How does that work? So far I haven't succeed in achieving this. Some help with this please?