Unable to login with great-child theme

Has anyone else successfully created and used a child theme for Great theme? When I attempt to activate the child theme, I get the following error message when I attempt to login (from a second computer) after the change:
ERROR: Cookies are blocked due to unexpected output.
The login is not successful.

As soon as I switch back to the parent theme, the error goes away.

The only 2 things in my child theme (named great-child) are:
functions.php
<?php
add_action( ‘wp_enqueue_scripts’, ‘theme_enqueue_styles’ );
function theme_enqueue_styles() {
wp_enqueue_style( ‘parent-style’, get_template_directory_uri() . ‘/style.css’ );
}
?>

and style.css
/*
Theme Name: Great Child
Description: Child theme for Great theme for Newfield website
Author: my name
Version: 1.0.0
Template: great
License: GNU General Public License v2 or later
License URI: https://www.gnu.org/licenses/gpl-2.0.html
Text Domain: great-child
*/
.post-box img {
float: none;
}

Any ideas of what I have done wrong?
Thanks,
Linda