If you’re including your ACF color picker on an Options Page, you’ll need to say that in your php when you get the field. Also don’t forget your CSS semicolons:
<style>
:root {
--color-1: <?php the_field( 'color_1', 'option' ); ?>;
--color-2: <?php the_field( 'color_2', 'option' ); ?>;
--color-3: <?php the_field( 'color_3', 'option' ); ?>;
}
</style>
