fix(package): Downgrade cssnano version

dist/openplayer.js

@@ -46,19 +46,34 @@ return /******/ (function(modules) { // webpackBootstrap
 /******/ 	// define getter function for harmony exports
 /******/ 	__webpack_require__.d = function(exports, name, getter) {
 /******/ 		if(!__webpack_require__.o(exports, name)) {
-/******/ 			Object.defineProperty(exports, name, {
-/******/ 				configurable: false,
-/******/ 				enumerable: true,
-/******/ 				get: getter
-/******/ 			});
+/******/ 			Object.defineProperty(exports, name, { enumerable: true, get: getter });
 /******/ 		}
 /******/ 	};
 /******/
 /******/ 	// define __esModule on exports
 /******/ 	__webpack_require__.r = function(exports) {
+/******/ 		if(typeof Symbol !== 'undefined' && Symbol.toStringTag) {
+/******/ 			Object.defineProperty(exports, Symbol.toStringTag, { value: 'Module' });
+/******/ 		}
 /******/ 		Object.defineProperty(exports, '__esModule', { value: true });
 /******/ 	};
 /******/
+/******/ 	// create a fake namespace object
+/******/ 	// mode & 1: value is a module id, require it
+/******/ 	// mode & 2: merge all properties of value into the ns
+/******/ 	// mode & 4: return value when already ns object
+/******/ 	// mode & 8|1: behave like require
+/******/ 	__webpack_require__.t = function(value, mode) {
+/******/ 		if(mode & 1) value = __webpack_require__(value);
+/******/ 		if(mode & 8) return value;
+/******/ 		if((mode & 4) && typeof value === 'object' && value && value.__esModule) return value;
+/******/ 		var ns = Object.create(null);
+/******/ 		__webpack_require__.r(ns);
+/******/ 		Object.defineProperty(ns, 'default', { enumerable: true, value: value });
+/******/ 		if(mode & 2 && typeof value != 'string') for(var key in value) __webpack_require__.d(ns, key, function(key) { return value[key]; }.bind(null, key));
+/******/ 		return ns;
+/******/ 	};
+/******/
 /******/ 	// getDefaultExport function for compatibility with non-harmony modules
 /******/ 	__webpack_require__.n = function(module) {
 /******/ 		var getter = module && module.__esModule ?