Added variable to set page class.

assets/templates/base.pug

@@ -4,9 +4,12 @@ html(class="no-js", lang="en")
 	block set_site_root
 		- var site_root = './'
 
+	block set_current_page
+		- var page = 'default'
+
 	include ./html_head.pug
 
-	body
+	body(class=page)
 		include ./header.pug
 
 		#content

index.pug

@@ -6,4 +6,7 @@
 
 extend ./assets/templates/base.pug
 
+block set_current_page
+	- var page = 'index'
+
 block content