.btn-scroll{opacity:0;transition:opacity 0.5s;z-index:9999}.btn-scroll.mostrar{opacity:1}@keyframes blinking{0%{box-shadow:0 0 0 0 rgba(183,167,139,0.75)}70%{box-shadow:0 0 0 15px rgba(183,167,139,0.1)}100%{box-shadow:0 0 0 0 rgba(183,167,139,0)}}.elemento-fijo{animation:blinking 2.5s ease infinite}