Header scroll shadow

UX
4

You can add something like to the header tab of your theme

<div class="header-anchor"></div>

<script type="text/discourse-plugin" version="0.8">
if (!"IntersectionObserver" in window) return;

const { on } = require("discourse-common/utils/decorators");

const stickyClass = "sticky";

api.modifyClass("component:site-header", {
  @on("didInsertElement")
  stickyHeaderCheck() {
    const anchor = document.querySelector(".header-anchor");
    const header = this.element;

    new IntersectionObserver(entries => {
      if (!entries[0].isIntersecting) {
        header.classList.add(stickyClass);
      } else {
        header.classList.remove(stickyClass);
      }
    }).observe(anchor);
  }
});
</script>

This will add a sticky class to the header wrapper and allows you to set custom css when the header is “stuck” to the top as you scroll

.d-header {
  box-shadow: none;
  transition: box-shadow 0.3s ease-in-out;
  will-change: box-shadow;
  .sticky & {
    box-shadow: 0 3px 5px rgba(57, 63, 72, 0.3);
  }
}
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