Sass (scss) & overriding default variables/lists/maps & some custom class/mixin generation (via nested each & includes). I personally like to default to utility

Sass (scss) & overriding default variables/lists/maps & some custom class/mixin generation (via nested each & includes). I personally like to default to utility classes (builtin + custom) and only build components when they get apparent during development. This is for bespoke designs. YMMV