см.
var wpFrontProductCustDetail = { ..., "product_cust_detail_title_font_color":"#000000", ...}
далее, в
/wp-content/plugins/customize-woocommerce-shop/includes/js/woo-product-customizer-front-detail.js
строки 24-27
// detail page title settings
$('.product .product_title').attr('style','color: '+wpFrontProductCustDetail.product_cust_detail_title_font_color+ ' !important; font-size: '+wpFrontProductCustDetail.product_cust_detail_title_font_size+ 'px !important; font-weight: '+wpFrontProductCustDetail.product_cust_detail_title_font_weight+ ' !important;');
$('.product .products h3').attr('style','color: '+wpFrontProductCustDetail.product_cust_detail_title_font_color+ ' !important; font-size: '+wpFrontProductCustDetail.product_cust_detail_title_font_size+ 'px !important; font-weight: '+wpFrontProductCustDetail.product_cust_detail_title_font_weight+ ' !important;');
$('.repupress_customize_woocommerce_productom_class .product_title').attr('style','color: '+wpFrontProductCustDetail.product_cust_detail_title_font_color+ ' !important; font-size: '+wpFrontProductCustDetail.product_cust_detail_title_font_size+ 'px !important; font-weight: '+wpFrontProductCustDetail.product_cust_detail_title_font_weight+ ' !important;');
$('.repupress_customize_woocommerce_productom_class .products h1,.repupress_customize_woocommerce_productom_class .products h2,.repupress_customize_woocommerce_productom_class .products h3,.repupress_customize_woocommerce_productom_class .products h4,.repupress_customize_woocommerce_productom_class .products h5').attr('style','color: '+wpFrontProductCustDetail.product_cust_detail_title_font_color+ ' !important; font-size: '+wpFrontProductCustDetail.product_cust_detail_title_font_size+ 'px !important; font-weight: '+wpFrontProductCustDetail.product_cust_detail_title_font_weight+ ' !important;');
Firebug is your freind )