diff --git a/runtime/main/app/bundle.ts b/runtime/main/app/bundle.ts
index a7b382f1..c7ccf1df 100644
--- a/runtime/main/app/bundle.ts
+++ b/runtime/main/app/bundle.ts
@@ -39,6 +39,8 @@ import { App } from './App';
 
 const APP_LIFE_CYCLE_TYPES: string[] = ['onCreate', 'onError', 'onDestroy', 'onShow', 'onHide'];
 
+export let CSS_INHERITANCE: string[];
+
 /**
  * Parse app page code.
  * @param {Page} page
@@ -49,7 +51,7 @@ const APP_LIFE_CYCLE_TYPES: string[] = ['onCreate', 'onError', 'onDestroy', 'onS
 export const defineFn = function(page: Page, packageName: string, name?: string, ...args: any[] | null): void {
   Log.debug(`Define a page ${name}.`);
   const parseContent: Function = args[1];
-  let bundleContent: object = null;
+  let bundleContent: any = null;
 
   // Function to obtain bundle content.
   if (parseContent) {
@@ -65,6 +67,14 @@ export const defineFn = function(page: Page, packageName: string, name?: string,
     const moduleContent = { exports: {} };
     parseContent(pageRequire, moduleContent.exports, moduleContent);
     bundleContent = moduleContent.exports;
+
+    let minPlatformVersion: number = 5;
+    if (bundleContent.manifest) {
+      minPlatformVersion = bundleContent.manifest.minPlatformVersion;
+    }
+    CSS_INHERITANCE = minPlatformVersion > 5 ?
+      ['fontFamily', 'fontWeight', 'fontSize', 'fontStyle', 'textAlign', 'lineHeight', 'letterSpacing', 'color', 'visibility'] :
+      [];
   }
 
   // Apply bundleContent.
diff --git a/runtime/main/model/compiler.ts b/runtime/main/model/compiler.ts
index 8f6e1781..1e0c653c 100644
--- a/runtime/main/model/compiler.ts
+++ b/runtime/main/model/compiler.ts
@@ -730,11 +730,11 @@ function watchBlock(vm: Vm, fragBlock: FragBlockInterface, calc: Function, type:
  */
 function mergeContext(context: Vm, mergedData: object): any {
   const newContext = Object.create(context);
-  newContext.data = mergedData;
-  newContext.shareData = {};
+  newContext._data = mergedData;
+  newContext._shareData = {};
   initData(newContext);
   initComputed(newContext);
-  newContext.realParent = context;
+  newContext._realParent = context;
   return newContext;
 }
 
diff --git a/runtime/main/model/directive.ts b/runtime/main/model/directive.ts
index e6e8761d..0d3aaf08 100644
--- a/runtime/main/model/directive.ts
+++ b/runtime/main/model/directive.ts
@@ -513,6 +513,18 @@ function selectStyle(css: object, key: string, vm: Vm): any {
  * @param {string[]} classList - List of class label.
  */
 function setClassStyle(el: Element, css: object, classList: string[], vm?: Vm): void {
+  const SPACE_REG: RegExp = /\s+/;
+  const newClassList: string[] = [];
+  if (Array.isArray(classList)) {
+    classList.forEach(v => {
+      if (typeof v === 'string' && SPACE_REG.test(v)) {
+        newClassList.push(...v.trim().split(SPACE_REG));
+      } else {
+        newClassList.push(v);
+      }
+    });
+  }
+  classList = newClassList;
   const classStyle = {};
   const length = classList.length;
   if (length === 1) {
@@ -681,7 +693,9 @@ function setAnimation(style: any, css: any): void {
   const keyframes = css['@KEYFRAMES'];
   if (animationName && keyframes) {
     style['animationName'] = keyframes[animationName];
-    style['animationName'].push({'animationName': animationName});
+    if (style['animationName']) {
+      style['animationName'].push({'animationName': animationName});
+    }
   }
 }
 
diff --git a/runtime/main/model/index.ts b/runtime/main/model/index.ts
index 683c3d84..6783c1d7 100755
--- a/runtime/main/model/index.ts
+++ b/runtime/main/model/index.ts
@@ -444,11 +444,13 @@ export default class Vm {
    * @param {*} value - Property
    */
   public $set(key: string, value: any): void {
-    if (typeof key !== 'string' || key.indexOf('.') === -1) {
+    if (typeof key !== 'string') {
       Log.warn(`Invalid parameter type: The type of 'key' should be string with '.', not ${typeof key}.`);
       return;
     }
-    _proxySet(this.data, key, value);
+    if (key.indexOf('.') !== -1) {
+      _proxySet(this.data, key, value);
+    }
     set(this.data, key, value);
   }
 
@@ -544,12 +546,15 @@ export default class Vm {
   /**
    * Type of this Vm.
    * @type {string}
-   * @readonly
    */
   public get type() {
     return this._type;
   }
 
+  public set type(newType) {
+    this._type = newType;
+  }
+
   /**
    * Css of this Vm.
    * @type {[key: string]: any}
@@ -886,6 +891,9 @@ function getRoot(vm: any): Vm {
  * @param {Element} el - Element object.
  */
 function fireNodeDetached(el: Element) {
+  if (!el) {
+    return;
+  }
   if (el.event && el.event['detached']) {
     el.fireEvent('detached', {});
   }
diff --git a/runtime/main/reactivity/state.js b/runtime/main/reactivity/state.js
index e8c58456..3c7c456a 100644
--- a/runtime/main/reactivity/state.js
+++ b/runtime/main/reactivity/state.js
@@ -120,6 +120,10 @@ function proxyMethods(vm, key) {
     enumerable: true,
     get: function proxyGetter () {
       return vm._methods[key];
+    },
+    set: function proxySetter(newMethod) {
+      vm._methods[key] = typeof newMethod === 'function' && key !== 'data' ?
+        newMethod.bind(vm) : newMethod;
     }
-  })
+  });
 }
diff --git a/runtime/vdom/Element.ts b/runtime/vdom/Element.ts
index c7d14451..f36c673c 100644
--- a/runtime/vdom/Element.ts
+++ b/runtime/vdom/Element.ts
@@ -28,8 +28,7 @@ import Document from './Document';
 import { TaskCenter } from '../main/manage/event/TaskCenter';
 import { FragBlockInterface } from '../main/model/compiler';
 import Vm from '../main/model';
-
-const CSS_INHERITANCE: string[] = ['fontFamily', 'fontWeight', 'fontSize', 'fontStyle', 'textAlign', 'lineHeight', 'letterSpacing', 'color', 'visibility'];
+import { CSS_INHERITANCE } from '../main/app/bundle';
 
 /**
  * Element is a basic class to describe a tree node in vdom.
@@ -842,27 +841,29 @@ class Element extends Node {
    * @param {*} dest - Target style object.
    */
   public assignStyle(src: any, dest: any): void {
-    const keys = Object.keys(dest);
+    if (dest) {
+      const keys = Object.keys(dest);
 
-    // Margin and padding style: the style should be empty in the first.
-    keys.sort(function(style1, style2) {
-      if (dest[style1] === '') {
-        return 1;
-      } else {
-        return -1;
-      }
-    });
-    let i = keys.length;
-    while (i--) {
-      const key = keys[i];
-      const val = dest[key];
-      if (val) {
-        src[key] = val;
-      } else {
-        if ((val === '' || val === undefined) && src[key]) {
-          return;
+      // Margin and padding style: the style should be empty in the first.
+      keys.sort(function(style1, style2) {
+        if (dest[style1] === '') {
+          return 1;
+        } else {
+          return -1;
+        }
+      });
+      let i = keys.length;
+      while (i--) {
+        const key = keys[i];
+        const val = dest[key];
+        if (val) {
+          src[key] = val;
+        } else {
+          if ((val === '' || val === undefined) && src[key]) {
+            return;
+          }
+          src[key] = val;
         }
-        src[key] = val;
       }
     }
   }
@@ -924,14 +925,13 @@ class Element extends Node {
     if (this._event && this._event['detached']) {
       this.fireEvent('detached', {});
     }
-    this._attr = null;
-    this._style = null;
+    this._attr = {};
+    this._style = {};
     this._classStyle = {};
-    this._event = null;
-    this._idStyle = null;
-    this._tagStyle = null;
+    this._event = {};
+    this._idStyle = {};
+    this._tagStyle = {};
     this._classList.length = 0;
-    this._classList = null;
 
     if (this.destroyHook) {
       this.destroyHook();
@@ -942,11 +942,9 @@ class Element extends Node {
         child.destroy();
       });
       this._children.length = 0;
-      this._children = null;
     }
     if (this._pureChildren) {
       this._pureChildren.length = 0;
-      this._pureChildren = null;
     }
     super.destroy();
   }