diff --git a/scss/grid-system/grid-system.scss b/scss/grid-system/grid-system.scss
index 982dbc1..697858f 100644
--- a/scss/grid-system/grid-system.scss
+++ b/scss/grid-system/grid-system.scss
@@ -127,10 +127,34 @@
   }
 }
 
+@mixin helpers {
+  [class*='content-'] {
+    &[class*='-left'] {
+      @include content-align(left null);
+    }
+    &[class*='-center'] {
+      @include content-align(center null);
+    }
+    &[class*='-right'] {
+      @include content-align(right null);
+    }
+    &[class*='-top'] {
+      @include content-align(null top);
+    }
+    &[class*='-middle'] {
+      @include content-align(null middle);
+    }
+    &[class*='-bottom'] {
+      @include content-align(null bottom);
+    }
+  }
+}
+
 @mixin grid-system($columns: $columns-default, $gutter: $gutter-default) {
   // Grid system
   // --------------------------------------------------
   @include containers($gutter);
   @include rows($gutter);
   @include columns($columns, $gutter);
+  @include helpers;
 }
diff --git a/scss/mixins/_overflow.scss b/scss/mixins/_overflow.scss
index 12c3221..8f3c3f7 100644
--- a/scss/mixins/_overflow.scss
+++ b/scss/mixins/_overflow.scss
@@ -1,6 +1,6 @@
 @charset 'UTF-8';
 
-$overflow-modes: array-concat((visible, hidden, scroll, auto), $css-default-modes);
+$overflow-modes: array-concat((visible, hidden, scroll, overlay, unset, auto), $css-default-modes);
 
 @function is-overflow-mode($o) {
   @return is-defined($o) and array-contains($overflow-modes, $o);