ENGCOM-4051: [CMS] Improving the uploaded images styling view #20787

 - Merge Pull Request #20787 from eduard13/magento2:2.3-develop-file-upload-styling-view
 - Merged commits:
   1. 0614a9a
   2. 24221c9

Author: magento-engcom-team

app/design/adminhtml/Magento/backend/web/css/source/components/_popups.less

@@ -264,7 +264,7 @@
             }
         }
 
-        #contents-uploader {
+        .contents-uploader {
             margin: 0 0 @indent__base;
         }
 
@@ -311,7 +311,7 @@
             }
         }
 
-        #contents-uploader {
+        .contents-uploader {
             &:extend(.abs-clearfix all);
         }