refactor: make PL header sticky if supported

Author: sghoweri

packages/uikit-workshop/src/sass/scss/04-components/_header.scss

@@ -10,6 +10,7 @@
 */
 .pl-c-header {
   position: fixed;
+  position: sticky;
   top: 0;
   left: 0;
   z-index: 4;