metamask-extension/ui/components/component-library/button-link/button-link.scss

.mm-button-link {
  &:hover {
    opacity: 0.5;
  }

  &:active {
    opacity: 0.5;
  }

  &--disabled {
    &:hover {
      opacity: 0.3;
    }

    &:active {
      opacity: 0.3;
    }
  }

  &--type-danger {
    &:hover {
      color: var(--color-error-default);
      opacity: 0.5;
    }

    &:active {
      color: var(--color-error-default);
      opacity: 0.5;
    }
  }

  &--type-danger#{&}--disabled:hover {
    opacity: 0.3;
  }

  &--size-auto {
    height: auto;
  }

  &--size-inherit {
    height: auto;
    background-color: transparent;
    vertical-align: top;
    font-family: inherit;
    font-weight: inherit;
    font-size: inherit;
    line-height: inherit;
    letter-spacing: inherit;
  }
}