chore: use fixed position for the skip link

src/client/theme-default/components/VPSkipLink.vue

@@ -17,6 +17,7 @@ function focusOnTargetAnchor({ target }: Event) {
   const el = targetEl?.querySelector<HTMLAnchorElement>('main h1[id][tabindex="-1"]') ?? targetEl
 
   if (el) {
+    if (!el.hasAttribute('tabindex')) {
       const removeTabIndex = () => {
         el.removeAttribute('tabindex')
         el.removeEventListener('blur', removeTabIndex)
@@ -24,6 +25,7 @@ function focusOnTargetAnchor({ target }: Event) {
 
       el.setAttribute('tabindex', '-1')
       el.addEventListener('blur', removeTabIndex)
+    }
     el.focus()
     window.scrollTo(0, 0)
   }
@@ -43,6 +45,7 @@ function focusOnTargetAnchor({ target }: Event) {
 
 <style scoped>
 .VPSkipLink {
+  position: fixed;
   top: 8px;
   left: 8px;
   padding: 8px 16px;