.scroll-top-btn{position:fixed;bottom:40px;right:40px;background-color:#3498db;color:#fff;border:0;padding:10px 20px;border-radius:5px;cursor:pointer;font-size:16px;display:none;transition:opacity .3s}.scroll-top-btn:hover{background-color:#2980b9}@media screen and (max-width:600px){.scroll-top-btn{bottom:20px;right:20px;padding:8px 16px;font-size:14px}}