hladké rolovanie css
html {
scroll-behavior: smooth;
}
/* No support in IE, or Safari
You can use this JS polyfill for those */
http://iamdustan.com/smoothscroll/
ako hladké rolovanie v JavaScripte
window.scrollTo({ top: 900, behavior: 'smooth' })
hladké posúvanie.js
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/smooth-scroll/16.1.0/smooth-scroll.min.js"></script>