pe-shortcode-content-boxed-style.php

<?php

/** Enqueuing the Stylesheet for two shortcode */

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

pe-shortcode-content-boxed.php

<?php

/**
 * [boxed] returns the HTML code for a content box with colored titles.
 * @return string HTML code for boxed content
 */

add_shortcode( 'boxed', 'pe_content_boxed' );
/**
 * Shortcode Using $content
 *
 * @param $atts
 * @param null $content
 * @param string $tag
 *
 * @return string
 */
function pe_content_boxed( $atts, $content = null, $tag = '' ) {
    $a = shortcode_atts( array(
      'title' => 'Title',
      'title_color' => 'white',
      'color' => 'blue',
    ), $atts );

    return '<div class="pe-content-boxed" style="border:2px solid ' . esc_attr( $a['color'] ) . ';">' . '<div class="pe-boxed-title" style="background-color:' . esc_attr( $a['color'] ) . ';"><h3 style="color:' . esc_attr( $a['title_color'] ) . ';">' . esc_attr( $a['title'] ) . '</h3></div>' . '<div class="pe-boxed-content"><p>' . esc_attr( $content ) . '</p></div>' . '</div>';
}