<span class="preview-notice"><?php
/* translators: %s is the theme name in the Customize/Live Preview pane */
echo sprintf( __( 'You are previewing %s' ), '<strong class="theme-name">' . $wp_customize->theme()->display('Name') . '</strong>' );
<span class="preview-notice"><?php
/* translators: %s is the theme name in the Customize/Live Preview pane */
echo sprintf( __( 'You are previewing %s' ), '<strong class="theme-name">' . $wp_customize->theme()->display('Name') . '</strong>' );