update styling, set up domain

Author: chdeskur

fern/docs.yml

@@ -1,5 +1,7 @@
 instances:
   - url: vapi.docs.buildwithfern.com
+    # vv uncomment to go live vv
+    # custom-domain: docs.vapi.ai
 
 announcement: 
   message: "🚀 Vapi now provides server SDKs! Check out the [supported languages](/server-sdks)."
@@ -16,10 +18,10 @@ colors:
     dark: '#94ffd2'
     light: '#37aa9d'
   background:
-    dark: '#000000'
+    dark: '#121418'
     light: '#FFFFFF'
   header-background:
-    dark: '#000000'
+    dark: '#121418'
     light: '#FFFFFF'
 experimental:
   mdx-components: