Adding an e-mail icon to the top bar in Kerli Lite theme

Hello.
I am trying to add an e-mail genericon to the top bar, but it will not appear. https://www.everydaywritinglife.com

I’ve edited the inc/topbar.php file in a child theme.

<?php if( get_theme_mod( 'kerli_lite_mail_url' ) !== '' ) { ?>
						<a class="social social-mail" target="_blank" title="<?php _e( 'Subscribe by E-mail', 'kerli-lite' ); ?>" href="<?php echo esc_url(get_theme_mod( 'kerli_lite_mail_url', '' )); ?>"></a>
					<?php } ?>

I’ve also edited the inc/kerli-lite-customizer.php file in a child theme.

$wp_customize->add_setting('kerli_lite_mail_url', array('default' => 'https://everydaywritinglife.com', 'sanitize_callback' => 'kerli_lite_sanitize_text'));
	$wp_customize->add_control('kerli_lite_mail_url', array(
			'label' => __('Mail URL', 'kerli-lite'),
			'section' => 'kerli_lite_top_bar',
			'type' => 'text',
		));

I’ve also edited the style.css

.social-mail:before { content: '\f410'; } .social-mail:hover { color:#3B579B; }

However, the new option isn’t appearing in the Customizer, and the image isn’t appearing in the top bar. The hover and link seem to work because of the code in the kerli-lite-customizer.php file, but no icon appears.

What am I missing? Any guidance would be appreciated. Thanks!