BEM

styles.css

.button {
  /* */
}

.button--primary {
  /* */
}
.button--secondary {
  /* */
}

.button--small {
  /* */
}
.button--medium {
  /* */
}

.button--primary-small {
  /* */
}

import { cva } from "class-variance-authority";

const button = cva("button", {
  variants: {
    intent: {
      primary: "button--primary",
      secondary: "button--secondary",
    },
    size: {
      small: "button--small",
      medium: "button--medium",
    },
  },
  compoundVariants: [
    { intent: "primary", size: "medium", class: "button--primary-small" },
  ],
  defaultVariants: {
    intent: "primary",
    size: "medium",
  },
});

button();
// => "button button--primary button--medium"

button({ intent: "secondary", size: "small" });
// => "button button--secondary button--small"