Add display responsive classes

sass/base/helpers.sass

@@ -1,8 +1,31 @@
 // Display
 
-.is-flex
-  display: flex
+$displays: 'block' 'flex' 'inline' 'inline-block' 'inline-flex'
 
+@each $display in $displays
+  .is-#{$display}
+    display: #{$display}
+  .is-#{$display}-mobile
+    +mobile
+      display: #{$display} !important
+  .is-#{$display}-tablet
+    +tablet
+      display: #{$display} !important
+  .is-#{$display}-tablet-only
+    +tablet-only
+      display: #{$display} !important
+  .is-#{$display}-touch
+    +touch
+      display: #{$display} !important
+  .is-#{$display}-desktop
+    +desktop
+      display: #{$display} !important
+  .is-#{$display}-desktop-only
+    +desktop-only
+      display: #{$display} !important
+  .is-#{$display}-widescreen
+    +widescreen
+      display: #{$display} !important
 // Float
 
 .is-clearfix
@@ -40,6 +63,10 @@
     display: none !important
 
 .is-hidden-tablet
+  +tablet
+    display: none !important
+
+.is-hidden-tablet-only
   +tablet-only
     display: none !important
 
@@ -48,9 +75,17 @@
     display: none !important
 
 .is-hidden-desktop
+  +desktop
+    display: none !important
+
+.is-hidden-desktop-only
   +desktop-only
     display: none !important
 
+.is-hidden-widescreen
+  +widescreen
+    display: none !important
+
 // Other
 
 .is-disabled