tweak PageHeader demo style

src/components/PageHeader/demo/image.md

@@ -10,7 +10,7 @@ import PageHeader from 'ant-design-pro/lib/PageHeader';
 
 const content = (
   <div>
-    <p>段落示意：蚂蚁金服务设计平台-ant.design，用最小的工作量，无缝接入蚂蚁金服生态，
+    <p>段落示意：蚂蚁金服务设计平台 ant.design，用最小的工作量，无缝接入蚂蚁金服生态，
 提供跨越设计与开发的体验解决方案。</p>
     <div className="link">
       <a>
@@ -55,6 +55,9 @@ ReactDOM.render(
 ````
 
 <style>
+#scaffold-src-components-PageHeader-demo-image .code-box-demo {
+  background: #f2f4f5;
+}
 #scaffold-src-components-PageHeader-demo-image .imgContainer {
   margin-top: -60px;
   text-align: center;

src/components/PageHeader/demo/simple.md

@@ -24,3 +24,9 @@ ReactDOM.render(
   </div>
 , mountNode);
 ````
+
+<style>
+#scaffold-src-components-PageHeader-demo-simple .code-box-demo {
+  background: #f2f4f5;
+}
+</style>

src/components/PageHeader/demo/standard.md

@@ -93,3 +93,9 @@ ReactDOM.render(
   </div>
 , mountNode);
 ````
+
+<style>
+#scaffold-src-components-PageHeader-demo-standard .code-box-demo {
+  background: #f2f4f5;
+}
+</style>

src/components/PageHeader/demo/structure.md

@@ -41,7 +41,7 @@ ReactDOM.render(
 
 <style>
 #scaffold-src-components-PageHeader-demo-structure .code-box-demo {
-  background: #eee;
+  background: #f2f4f5;
 }
 #scaffold-src-components-PageHeader-demo-structure .logo {
   background: #3ba0e9;