docs: improve code demo box style (#26242)

* docs: improve code demo box style

* chore: update lighthouse.yml

* use node 14

.github/workflows/lighthouse-ci.yml

@@ -5,7 +5,9 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
-      - uses: actions/setup-node@v1
+      - uses: actions/setup-node@v2-beta
+        with:
+          node-version: '14'
       - run: npm install && npm install -g @lhci/cli@0.4.x
       - run: npm run site
       - run: lhci autorun --upload.target=temporary-public-storage

azure-pipelines.yml

@@ -23,7 +23,7 @@ stages:
           - task: NodeTool@0
             displayName: 'Install Node.js'
             inputs:
-              versionSpec: '12.13.1'
+              versionSpec: '14.7.0'
           - script: npm install
             displayName: 'Install modules'
           - script: |
@@ -53,7 +53,7 @@ stages:
           - task: NodeTool@0
             displayName: 'Install Node.js'
             inputs:
-              versionSpec: '12.13.1'
+              versionSpec: '14.7.0'
           - script: npm install
             displayName: 'Install modules'
           - script: |
@@ -71,7 +71,7 @@ stages:
           - task: NodeTool@0
             displayName: 'Install Node.js'
             inputs:
-              versionSpec: '12.16.3'
+              versionSpec: '14.7.0'
           - script: npm install
             displayName: 'Install modules'
           - script: |
@@ -98,7 +98,7 @@ stages:
           - task: NodeTool@0
             displayName: 'Install Node.js'
             inputs:
-              versionSpec: '12.13.1'
+              versionSpec: '14.7.0'
           - script: npm install
             displayName: 'Install modules'
           - task: DownloadPipelineArtifact@2

components/upload/demo/preview-file.md

@@ -33,13 +33,11 @@ const props = {
 };
 
 ReactDOM.render(
-  <>
-    <Upload {...props}>
-      <Button>
-        <UploadOutlined /> Upload
-      </Button>
-    </Upload>
-  </>,
+  <Upload {...props}>
+    <Button>
+      <UploadOutlined /> Upload
+    </Button>
+  </Upload>,
   mountNode,
 );
 ```

site/theme/static/demo.less

@@ -22,11 +22,6 @@
       background: @component-background;
     }
   }
-  .code-box-description {
-    p {
-      color: @site-text-color;
-    }
-  }
   &,
   .code-box-demo {
     background-color: @component-background;
@@ -140,7 +135,7 @@
     }
 
     blockquote {
-      margin: 0;
+      line-height: 1.5;
     }
 
     h4,