WooCommerce emails can have CSS inline styles added via an action hook woocommerce_email_header, to add your CSS styles use the hook like below… add_action( ‘woocommerce_email_header’, ‘bt_add_css_to_email’ ); /** * WooCommerce * Add inline CSS to emails sent out */ function bt_add_css_to_email() { echo ‘ <style type=”text/css”> h1 { text-align: center !important; color: #c7c9c7; } </style></pre>…