diff --git a/components/alert/demo/basic.md b/components/alert/demo/basic.md
index 206b0a4e88..fc15a669cf 100644
--- a/components/alert/demo/basic.md
+++ b/components/alert/demo/basic.md
@@ -20,7 +20,7 @@ ReactDOM.render(<Alert message="Success Text" type="success" />, mountNode);
 ```
 
 <style>
-.ant-alert {
+.code-box-demo .ant-alert {
   margin-bottom: 16px;
 }
 </style>
diff --git a/components/input-number/demo/size.md b/components/input-number/demo/size.md
index c2d56fe158..d5f2a4cf67 100644
--- a/components/input-number/demo/size.md
+++ b/components/input-number/demo/size.md
@@ -31,7 +31,7 @@ ReactDOM.render(
 ```
 
 ```css
-.ant-input-number {
+.code-box-demo .ant-input-number {
   margin-right: 10px;
 }
 ```
diff --git a/components/switch/demo/basic.md b/components/switch/demo/basic.md
index 64d329a600..f8f22062bf 100644
--- a/components/switch/demo/basic.md
+++ b/components/switch/demo/basic.md
@@ -24,7 +24,7 @@ ReactDOM.render(<Switch defaultChecked onChange={onChange} />, mountNode);
 ```
 
 <style>
-.ant-switch {
+.code-box-demo .ant-switch {
   margin-bottom: 8px;
 }
 </style>