feat: improve hash target positioning upon initial navigation

app/router.scrollBehavior.js

@@ -4,6 +4,22 @@ function timeout (t) {
   })
 }
 
+let paddingTopInPixels = null
+function getScrollPaddingTopInPixels () {
+  if (paddingTopInPixels !== null) {
+    return paddingTopInPixels
+  }
+  const measurer = document.createElement('div')
+  const paddingTop = getComputedStyle(document.documentElement).scrollPaddingTop
+  measurer.style.position = 'absolute'
+  measurer.style.visibility = 'hidden'
+  measurer.style.height = paddingTop
+  document.body.appendChild(measurer)
+  paddingTopInPixels = measurer.offsetHeight
+  measurer.remove()
+  return paddingTopInPixels
+}
+
 export default async function scrollBehavior (to) {
   if (to.hash) {
     // scroll to anchor by returning the selector
@@ -11,7 +27,7 @@ export default async function scrollBehavior (to) {
     return {
       selector: decodeURIComponent(to.hash),
       offset: {
-        y: 120
+        y: getScrollPaddingTopInPixels()
       }
     }
   }