Bento generates invalid inline CSS on posts

I noticed today that our Bento theme is generating the following CSS in the bento-theme-styles-inline-css section on posts:

			.post-header-title h1,
			.entry-header h1 { 
				color: ; 
			}
			.post-header-subtitle {
				color: #999999;
			}
			.site-content {
				background-color: ;
			}

This is obviously invalid. It looks like it comes from bento_insert_custom_styles() on line 413 of functions.php:

        if ( is_singular() || ( is_home() && 'page' == get_option( 'show_on_front' ) ) ) {
                $custom_css .= ' 
                        .post-header-title h1,
                        .entry-header h1 { 
                                color: '.esc_html( get_post_meta( $postid, 'bento_title_color', true ) ).'; 
                        }
                        .post-header-subtitle {
                                color: '.esc_html( get_post_meta( $postid, 'bento_subtitle_color', true ) ).'; 
                        }
                        .site-content {
                                background-color: '.esc_html( get_post_meta( $postid, 'bento_page_background_color', true ) ).'; 
                        }
                ';

Presumably this should be checking if the post_meta items it retrieves are empty and only including the relevant CSS if not?