Bootstrap tag helpers demo.css changes

framework/test/Volo.Abp.AspNetCore.Mvc.UI.Bootstrap.Demo/wwwroot/css/demo.css

@@ -1,10 +1,17 @@
 .demo-with-code {
   padding-bottom: 10px;
-  margin-bottom: 10px; }
+  margin-bottom: 10px;
+    margin-top: 20px; }
+    .demo-with-code .attribute-area {
+        padding: 10px;
+    }
   .demo-with-code .demo-area {
-    margin-bottom: 1em; }
+      border: 1px solid #ddd;
+      padding: 20px;
+  }
   .demo-with-code .code-area {
     border: 1px solid #ddd;
     padding: 10px;
-    font-size: 0.9em; }
+    font-size: 0.9em; 
+  }