Make subnavigation a bit darker color

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/assets/stylesheets/framework/nav.scss

@@ -77,10 +77,10 @@
 
   &.sub-nav {
     text-align: center;
-    background-color: $background-color;
+    background-color: $dark-background-color;
 
     .container-fluid {
-      background-color: $background-color;
+      background-color: $dark-background-color;
       margin-bottom: 0;
     }
 

app/assets/stylesheets/framework/variables.scss

@@ -12,10 +12,11 @@ $sidebar-breakpoint: 1024px;
 /*
  * UI elements
  */
-$border-color:       #e5e5e5;
-$focus-border-color: #3aabf0;
-$table-border-color: #f0f0f0;
-$background-color:   #fafafa;
+$border-color:          #e5e5e5;
+$focus-border-color:    #3aabf0;
+$table-border-color:    #f0f0f0;
+$background-color:      #fafafa;
+$dark-background-color: #f7f7f7;
 
 /*
  * Text
@@ -153,9 +154,6 @@ $warning-message-bg: #fbf2d9;
 $warning-message-color: #9e8e60;
 $warning-message-border: #f0e2bb;
 
-/* header */
-$light-grey-header: #faf9f9;
-
 /* tanuki logo colors */
 $tanuki-red: #e24329;
 $tanuki-orange: #fc6d26;