.wp-block-button.is-style-outline[class]
  > .wp-block-button__link:not(.has-text-color, .has-background) {
  box-shadow: var(--wp--preset--shadow--button-outline);
}

.wp-block-button.is-style-outline[class]
  > .wp-block-button__link:not(.has-text-color, .has-background):hover {
  color: var(--wp--preset--color--heading);
}