Sticky back-to-top link appearing after scrolling down one viewport height.
<a href="#!" class="position-relative top-0 btn-scroll-top"> <svg class="progress-square svg-content" width="100%" height="100%" viewBox="0 0 40 40"> <path d="M8 1H32C35.866 1 39 4.13401 39 8V32C39 35.866 35.866 39 32 39H8C4.13401 39 1 35.866 1 32V8C1 4.13401 4.13401 1 8 1Z" /> </svg> </a>