Add themes documentation (home-assistant#2966)

andrey-git · balloob · commit 372bb97a4530 · 2017-07-12T18:08:38.000-07:00
diff --git a/source/_components/frontend.markdown b/source/_components/frontend.markdown
@@ -17,3 +17,22 @@ This offers the official frontend to control Home Assistant.
 # Example configuration.yaml entry
 frontend:
 ```
+
+#### Themes
+Starting with version 0.49 you can define themes:
+
+Example:
+```yaml
+frontend:
+  themes:
+    happy:
+      primary-color: pink
+    sad:
+      primary-color: blue
+```
+
+The example above defined two themes named `happy` and `sad`. For each theme you can set values for CSS variables. For a partial list of variables used by the main frontend see [ha-style.html](https://github.com/home-assistant/home-assistant-polymer/blob/master/src/resources/ha-style.html)
+
+There are 2 themes-related services:
+ - `frontend.reload_themes` - reloads theme configuration from yaml.
+ - `frontend.set_theme(name)` - sets backend-preferred theme name. 
