var css = document.createElement('style'); css.type = 'text/css'; var styles = `.category-container .categoryTitleWrapper h1, .category-container .categoryTitleWrapper h2, .category-container .categoryTitleWrapper h3 { font-size: 22px; font-weight: 300; }`; if (css.styleSheet) css.styleSheet.cssText = styles; else css.appendChild(document.createTextNode(styles)); document.getElementsByTagName("head")[0].appendChild(css);