Added responsive flex-flow wrap attribute for rows and min-width for columns

vue-theme/src/sss/_helpers.sss

@@ -23,10 +23,14 @@
             align-items: center
     &-row
         flex-direction: row
+        flex-flow: wrap
     &-col
         flex-direction: column
+        min-width: 300px
     &-grow
         flex-grow: 1
+    /* &-wrap
+        flex-flow: wrap */
 
 .b
     &-radius