Customizations for default WordPress password protected pages / posts

functions.php

<?php 

// Add a custom class to the body for password posts / pages only
function add_password_protected_body_class( $classes ) {
if ( post_password_required() ) 
   $classes[] = 'wp-password-page';
   return $classes;
}
add_filter( 'body_class', 'add_password_protected_body_class' );

// Reformat the password message and form fields
function my_custom_password_form() {
  
    global $post;

    // Custom logic for the message
    $password_form_message = 
    __( '<p>This content is password protected. Enter password below to view it:</p>' );

    // Put together the custom form using the dynamic message
    $label = 'pwbox-'.( empty( $post->ID ) ? rand() : $post->ID );
	
    $form = '<div class="container"><form class="post-password-form" action="' . esc_url( site_url( 'wp-login.php?action=postpass', 'login_post' ) ) . '" method="post">' . $password_form_message . '<label id="password-label" for="' . $label . '">' . __( "Password:" ) . ' </label><input name="post_password" id="' . $label . '" class="pw-window" type="password" placeholder="Password" size="20" /><input type="submit" class="btn" name="Submit" value="' . esc_attr__( "Submit" ) . '" /></form></div>';
	
    return $form;
}
add_filter( 'the_password_form', 'my_custom_password_form' );

?>