fix a responsive grid (.row) issue

Author: sesemaya

assets/sass/mixins/_grid.scss

@@ -164,7 +164,7 @@
     }
 
     @include media-breakpoint-up(md) {
-      padding-right: ($grid-gutter-width-md-up / -2);
-      padding-left: ($grid-gutter-width-md-up / -2);
+      margin-right: ($grid-gutter-width-md-up / -2);
+      margin-left: ($grid-gutter-width-md-up / -2);
     }
   }

css/material.css

@@ -1588,8 +1588,8 @@ p {
 }
 @media (min-width: 960px) {
   .row {
-    padding-right: -0.75rem;
-    padding-left: -0.75rem;
+    margin-right: -0.75rem;
+    margin-left: -0.75rem;
   }
 }