Responsive sticky top (#29158)

scss/helpers/_position.scss

@@ -18,10 +18,17 @@
   z-index: $zindex-fixed;
 }
 
-.sticky-top {
-  @supports (position: sticky) {
-    position: sticky;
-    top: 0;
-    z-index: $zindex-sticky;
+// Responsive sticky top
+@supports (position: sticky) {
+  @each $breakpoint in map-keys($grid-breakpoints) {
+    @include media-breakpoint-up($breakpoint) {
+      $infix: breakpoint-infix($breakpoint, $grid-breakpoints);
+
+      .sticky#{$infix}-top {
+        position: sticky;
+        top: 0;
+        z-index: $zindex-sticky;
+      }
+    }
   }
 }

site/content/docs/4.3/helpers/position.md

@@ -31,3 +31,14 @@ Position an element at the top of the viewport, from edge to edge, but only afte
 {{< highlight html >}}
 <div class="sticky-top">...</div>
 {{< /highlight >}}
+
+## Responsive sticky top
+
+Responsive variations also exist for `.sticky-top` utility.
+
+{{< highlight html >}}
+<div class="sticky-sm-top">Stick to the top on viewports sized SM (small) or wider</div>
+<div class="sticky-md-top">Stick to the top on viewports sized MD (medium) or wider</div>
+<div class="sticky-lg-top">Stick to the top on viewports sized LG (large) or wider</div>
+<div class="sticky-xl-top">Stick to the top on viewports sized XL (extra-large) or wider</div>
+{{< /highlight >}}