Removed sticky from mobile

assets/sass/_theme/design-system/header.sass

 header[role="banner"]
-    @if $header-sticky-enabled
-        background-color: $header-background-color
-        position: sticky
-        top: 0
-        transition: transform $header-sticky-transition
-        z-index: 10
-        html.is-scrolling-down:not(.is-menu-open) &
-            &:not(:hover)
-                transform: translateY(-100%)
-
-        &.is-sticky
+    background-color: $header-background-color
+    position: fixed
+    z-index: 10
+    @include media-breakpoint-up(md)
+        @if $header-sticky-enabled
             position: sticky
+            top: 0
+            transition: transform $header-sticky-transition
+            html.is-scrolling-down:not(.is-menu-open) &
+                &:not(:hover)
+                    transform: translateY(-100%)
+
+            &.is-sticky
+                position: sticky
     @include media-breakpoint-down(md)
         padding: 1rem 0
+        width: 100%
 
     nav[role="navigation"]
         .container