Source: templates/emails/learner-completed-course.php

<?php
/**
 * Learner completed course email
 *
 * @author  Automattic
 * @package Sensei/Templates/Emails/HTML
 * @version 2.0.0
 */

// phpcs:disable VariableAnalysis.CodeAnalysis.VariableAnalysis.UndefinedVariable

if ( ! defined( 'ABSPATH' ) ) {
	exit;
} // Exit if accessed directly ?>

<?php

// Get data for email content
global $sensei_email_data;
extract( $sensei_email_data );

// For gmail compatibility, including CSS styles in head/body are stripped out therefore styles need to be inline. These variables contain rules which are added to the template inline. !important; is a gmail hack to prevent styles being stripped if it doesn't like something.
$small = 'text-align: center !important;';

$large = 'text-align: center !important;font-size: 350% !important;line-height: 100% !important;';

?>

<?php
/**
 * Action hook before email content.
 *
 * @hook sensei_before_email_content
 *
 * @param {string} $template Template name.
 */
do_action( 'sensei_before_email_content', $template );
?>

<p style="<?php echo esc_attr( $small ); ?>">
<?php
// translators: Placeholder is the translated text for "passed" or "failed".
printf( esc_html__( 'You have completed and %1$s the course', 'sensei-lms' ), esc_html( $passed ) );
?>
</p>

<h2 style="<?php echo esc_attr( $large ); ?>"><?php echo esc_html( get_the_title( $course_id ) ); ?></h2>

<?php
/**
 * Action hook after email content.
 *
 * @hook sensei_after_email_content
 *
 * @param {string} $template Template name.
 */
do_action( 'sensei_after_email_content', $template );
?>