remove unused variables

app/assets/stylesheets/content/_notifications.sass

@@ -32,7 +32,6 @@
 $nm-font-size: rem-calc(13px)
 $nm-border-radius: rem-calc(2px)
 $nm-box-padding: rem-calc(10px 35px 10px 35px)
-$nm-default-background: #fff
 $nm-font-color: $body-font-color
 
 $nm-color-error-border: #ca3f3f
@@ -47,9 +46,9 @@ $nm-color-warning-border: #b5b078
 $nm-color-warning-icon: #000
 $nm-color-warning-background: #f4f4aa
 
-$nm-color-simple-border: #8fc0db
-$nm-color-simple-background: #e3f5ff
-$nm-padding-simple-box: rem-calc(10px)
+$nm-color-default-border: #8fc0db
+$nm-color-default-background: #e3f5ff
+$nm-padding-default-box: rem-calc(10px)
 
 %nm-icon-error
   @extend .icon-attention2:before
@@ -73,13 +72,13 @@ $nm-padding-simple-box: rem-calc(10px)
 
 .notification-box
   box-shadow: rem-calc(1px 2px 3px) #dddddd
-  border: rem-calc(1px) solid $nm-color-simple-border
-  padding: $nm-padding-simple-box
+  border: rem-calc(1px) solid $nm-color-default-border
+  padding: $nm-padding-default-box
   border-radius: $nm-border-radius
   font-size: $nm-font-size
   position: relative
   word-wrap: break-word
-  background-color: $nm-color-simple-background
+  background-color: $nm-color-default-background
   color: $nm-font-color
 
   & .button