node-webshot enhancement

webshot.phantom.js

    // Handle customCSS option
    if (typeof options.customCSS === 'string') {
      page.evaluate(function(customCSS) {
        var style = document.createElement('style');
        var text  = document.createTextNode(customCSS);
        style.setAttribute('type', 'text/css');
        style.appendChild(text);
        document.head.insertBefore(style, document.head.firstChild);
      }, options.customCSS);
    }

Any reason why the style is inserted first, rather than last?