perf: optimizing page transition (#178)

* perf: optimizing page transition

* fix: minor fixes

src/components/control/BackToTop.astro

@@ -44,14 +44,4 @@ import { Icon } from 'astro-icon/components'
 function backToTop() {
     window.scroll({ top: 0, behavior: 'smooth' });
 }
-
-function scrollFunction() {
-    let btn = document.getElementById('back-to-top-btn');
-    if (document.body.scrollTop > 600 || document.documentElement.scrollTop > 600) {
-        btn.classList.remove('hide')
-    } else {
-        btn.classList.add('hide')
-    }
-}
-window.onscroll = scrollFunction
 </script>