pe-shortcode-cta-button-style.php

<?php

/** Enqueuing the Stylesheet for the CTA Button Shortcode */

function pe_cta_enqueue_scripts() {
     global $post;

     if( is_a( $post, 'WP_Post' ) && has_shortcode( $post->post_content, 'pe_cta_button_shortcode') ) {
     wp_register_style( 'pe-cta-stylesheet',  plugin_dir_url( __FILE__ ) . 'css/pe-cta-style.css' );
         wp_enqueue_style( 'pe-cta-stylesheet' );
     }
  
}
add_action( 'wp_enqueue_scripts', 'pe_cta_enqueue_scripts');

pe-shortcode-cta-button.php

<?php

/**
 * [pe_cta_button_shortcode] returns the HTML code for a CTA Button.
 * @return string Button HTML Code
*/

add_shortcode( 'pe_cta_button_shortcode', 'pe_cta_button' );
/**
 * Create a CTA Button Shortcode.
 *
 * @param $atts
 *
 * @return string
 */
function pe_cta_button( $atts ) {
	$a = shortcode_atts( array(
		'link' => '#',
		'id' => 'pe_cta_button',
		'color' => 'blue',
		'size' => '',
		'label' => 'Button',
		'target' => '_self'
	), $atts );

	return '<p><a href="' . esc_url( $a['link'] ) . '" id="' . esc_attr( $a['id'] ) . '" class="button ' . esc_attr( $a['color'] ) . ' ' . esc_attr( $a['size'] ) . '" target="' . esc_attr($a['target']) . '">' . esc_attr( $a['label'] ) . '</a></p>';
}