Merge pull request #421 from BeAPI/feature/sr-only-abstract-class

feat (sr-only): add abstact classes

Author: francoistibo

src/scss/04-utilities/_sr-only.scss

@@ -1,7 +1,15 @@
-.sr-only {
+%sr-only {
     @include sr-only;
 }
 
-.sr-only-focusable {
+%sr-only-focusable {
     @include sr-only(true);
 }
+
+.sr-only {
+    @extend %sr-only;
+}
+
+.sr-only-focusable {
+    @extend %sr-only-focusable;
+}