Copied from /js/nav.js

plugins/header.client.ts

@@ -0,0 +1,29 @@
+export default defineNuxtPlugin(() => {
+  if (process.server) return
+
+  window.addEventListener('scroll', () => {
+    const headerShadow = document.querySelector('.web-header-emit-shadow-when-top')
+    const headerAutohide = document.querySelector('.web-header-autohide')
+    if (!headerShadow && !headerAutohide) return
+
+    // --- Shadow when not at top ---
+    if (headerShadow) {
+      if (window.scrollY > 0) headerShadow.classList.add('shadow-active')
+      else headerShadow.classList.remove('shadow-active')
+    }
+
+    // --- Auto-hide logic ---
+    if (headerAutohide) {
+      const lastScrollY = Number(headerAutohide.getAttribute('data-last-scroll')) || 0
+      const currentScrollY = window.scrollY
+
+      if (currentScrollY > lastScrollY && currentScrollY > 0) {
+        headerAutohide.classList.add('web-header-hidden')
+      } else {
+        headerAutohide.classList.remove('web-header-hidden')
+      }
+
+      headerAutohide.setAttribute('data-last-scroll', String(currentScrollY))
+    }
+  })
+})