merging from ui update branch

wagtail/wagtailadmin/static/wagtailadmin/css/components/forms.less

@@ -227,7 +227,7 @@ input[type=submit], input[type=reset], input[type=button], .button, button{
     }
 
     &.button-small.bicolor{
-        padding-left:3em;
+        padding-left:3.5em;
 
         &:before{
             width:2em;

wagtail/wagtailadmin/static/wagtailadmin/css/core.less

@@ -250,9 +250,9 @@ img{
         /* search form */
         #menu-search{
             position:relative;
+
             .fields{
                 .transition(background-color 0.2s ease);
-                background-color:@color-grey-1;
                 border:0;
                 li{
                     border:0;

wagtail/wagtailadmin/static/wagtailadmin/css/layouts/page-editor.less

@@ -128,7 +128,7 @@
             font-family:Bitter, Georgia, serif;
             .border-radius(0px);
             border:0;
-            padding-top:3em;
+            padding-top:2em;
             padding-bottom:2em;
             font-size:1.2em;
             line-height:1.6em;