There is a :not selector in CSS. This will apply styles to everything, except elements that the not selector will target.
So, you could style the colors of all anchor tags except ones that you put a specific class on like:
a:not(.dontBeRed) {
color: red;
}
You can also target exceptions other ways. Lets say you have a few custom color utility classes, you could ignore elements that have any class with a certain prefix.
This will style all anchors red unless they have a class that starts with u-color
on them.
a:not([class*='u-color']) {
color: red;
}
.u-color--green {
color: green;
}
.u-color--blue {
color: blue;
}