Update custom-css.md

articles/hubs/custom-css.md

@@ -1,11 +1,17 @@
 # Custom CSS
 
+![Applying Custom CSS](https://github.com/stoplightio/docs/blob/develop/assets/gifs/hubs-custom-css.gif?raw=true)
+
+## What 
+
+Want to add some style and flair to your documentation? Add your own custom CSS to enhance your Hub’s look and feel. Below are the classes you can modify: 
+
 ```
 .Hub
   .HubHeader
     .HubHeader-section
       .HubHeaderItem.is-active
-        .HubHeaderItem-name 
+        .HubHeaderItem-name
   .HubMain
     .HubSidebar-overlay
     .HubSidebar-wrapper
@@ -17,7 +23,23 @@
         .HubPage-inner
           .HubPage-content
             .HubPageCrumbs
-              .HubPageCrumb
-            .HubPageBody
+              .HubPageCrumb 
+            .HubPageBody 
             .HubPageFooter
 ```
+
+## How
+
+1. Select the Hub you wish to modify 
+2. Select the **Design View**
+3. Click on **Theme** in the top toolbar 
+4. Select **Custom CSS** in the bottom left 
+5. Input CSS in the text area at the bottom of the page 
+6. Input CSS in the generated **theme** file (optional)
+7. In publishing, check the **Custom CSS** box under **Advanced** to apply the Custom CSS to that Hub when published
+
+>After accessing Custom CSS, a **theme** file will be generated under Documentation in the file explorer. After making changes to your CSS, make sure to save the **theme** file. 
+
+---
+**Related Articles**
+- [Theming](/documentation/design/theming)