スマート追従ヘッダ

<%# smart-sticky-header: the library only flips data-header-hidden from the scroll
    direction (and reveals on focus); the slide-away is this demo's CSS transform.
    Scroll down inside the frame to hide the bar, up (or Tab into it) to reveal. %>
<div class="smart-sticky-demo">
  <p class="smart-sticky-demo__hint"><%= t("components.smart_sticky_header.demo.hint") %></p>
  <div id="smart-sticky-viewport" class="smart-sticky-demo__viewport" role="region" tabindex="0"
       aria-label="<%= t('components.smart_sticky_header.demo.viewport_label') %>">
    <header class="smart-sticky-demo__header" data-controller="stimeo--smart-sticky-header"
            data-stimeo--smart-sticky-header-container-selector-value="#smart-sticky-viewport"
            data-stimeo--smart-sticky-header-offset-value="40">
      <a href="#smart-sticky-demo-content"><%= t("components.smart_sticky_header.demo.brand") %></a>
    </header>
    <div id="smart-sticky-demo-content" class="smart-sticky-demo__content">
      <% 10.times do |i| %>
        <p><%= t("components.smart_sticky_header.demo.paragraph", index: i + 1) %></p>
      <% end %>
    </div>
  </div>
</div>

/*
 * Presentation-only styles for the smart-sticky-header demo. The library flips
 * data-header-hidden; the slide-away transform (and its reduced-motion opt-out)
 * lives here. The controller is pointed at the demo's own scroll frame via
 * containerSelector (the catalog page itself does not scroll).
 */

.smart-sticky-demo__hint {
  margin: 0 0 0.75rem;
  color: var(--muted);
}

.smart-sticky-demo__viewport {
  position: relative;
  height: 16rem;
  overflow-y: auto;
  border: 1px solid var(--border);
  border-radius: 0.5rem;
}

.smart-sticky-demo__viewport:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.smart-sticky-demo__header {
  position: sticky;
  top: 0;
  padding: 0.75rem 1rem;
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  transition: transform 0.2s ease;
}

.smart-sticky-demo__header[data-header-hidden="true"] {
  transform: translateY(-100%);
}

@media (prefers-reduced-motion: reduce) {
  .smart-sticky-demo__header {
    transition: none;
  }
}

.smart-sticky-demo__content {
  padding: 1rem;
}

.smart-sticky-demo__content p {
  margin: 0 0 1.25rem;
  color: var(--fg);
}