#back-to-top{position:fixed;bottom:20px;right:20px;z-index:99;opacity:0;transition:opacity 0.5s} #back-to-top.show{opacity:1} #back-to-top img{width:7rem;height:7rem;transition:0.5s} #back-to-top:hover{cursor:pointer} @media only screen and (max-width:760px){#back-to-top img{width:4rem;height:4rem}}