diff --git a/wagtail/wagtailadmin/static/wagtailadmin/css/core.less b/wagtail/wagtailadmin/static/wagtailadmin/css/core.less
index 54f1e4f53..e0959fcc8 100644
--- a/wagtail/wagtailadmin/static/wagtailadmin/css/core.less
+++ b/wagtail/wagtailadmin/static/wagtailadmin/css/core.less
@@ -18,7 +18,7 @@ max z-index: 5;
 @import "components/formatters.less";
 
 html{
-    background-color:@color-header-bg;
+    background-color:@color-grey-5;
 }
 
 body{
@@ -378,7 +378,7 @@ body.explorer-open .nav-main{
 header{
     padding-top:1.5em;
     padding-bottom:1em;
-    background-color: @color-grey-5;
+    background-color: @color-header-bg;
     border-bottom:1px solid @color-grey-4;
     margin-bottom:2em;
 
diff --git a/wagtail/wagtailadmin/templates/wagtailadmin/shared/header.html b/wagtail/wagtailadmin/templates/wagtailadmin/shared/header.html
index 3039d801a..1db8ef277 100644
--- a/wagtail/wagtailadmin/templates/wagtailadmin/shared/header.html
+++ b/wagtail/wagtailadmin/templates/wagtailadmin/shared/header.html
@@ -1,13 +1,13 @@
-<header class="nice-padding {% if merged %}merged{% endif %} {% if tabbed %}tab-merged{% endif %} {% if form %}hasform{% endif %}">
+<header class="nice-padding {% if merged %}merged{% endif %} {% if tabbed %}tab-merged{% endif %} {% if search_form %}hasform{% endif %}">
     <div class="row row-flush">
-        <div class="left col{% if form %}6{% else %}9{% endif %}">
+        <div class="left col{% if search_form %}6{% else %}9{% endif %}">
             <h1>{{ title }} <span>{{ subtitle }}</span></h1>
         </div>
-        {% if form %}
+        {% if search_form %}
             <div class="left col3">
                 <form class="search-bar" action="{% url search_url %}" method="get">
                     <ul class="fields">
-                        {% for field in form %}
+                        {% for field in search_form %}
                             {% include "wagtailadmin/shared/field_as_li.html" with field=field %}
                         {% endfor %}
                         <li class="submit"><input type="submit" value="Search" /></li>
diff --git a/wagtail/wagtaildocs/views/documents.py b/wagtail/wagtaildocs/views/documents.py
index 17747049d..8b364f51c 100644
--- a/wagtail/wagtaildocs/views/documents.py
+++ b/wagtail/wagtaildocs/views/documents.py
@@ -57,7 +57,7 @@ def index(request):
         })
     else:
         return render(request, "wagtaildocs/documents/index.html", {
-            'form': form,
+            'search_form': form,
             'documents': documents,
             'popular_tags': Document.popular_tags(),
             'is_searching': is_searching,
diff --git a/wagtail/wagtailimages/views/images.py b/wagtail/wagtailimages/views/images.py
index f8d9eeb13..27230c313 100644
--- a/wagtail/wagtailimages/views/images.py
+++ b/wagtail/wagtailimages/views/images.py
@@ -57,7 +57,7 @@ def index(request):
         })
     else:
         return render(request, "wagtailimages/images/index.html", {
-            'form': form,
+            'search_form': form,
             'images': images,
             'is_searching': is_searching,
             'popular_tags': Image.popular_tags(),