.button-top{position:fixed;bottom:8rem;right:2rem;z-index:9999}
.button-top__btn{background:#152a69;color:white;border:0;width:48px;height:48px;font-size:24px;cursor:pointer;box-shadow:0 4px 10px rgba(0,0,0,0.2);transition:opacity .3s ease;padding-bottom:4px}