.back-to-top{position:fixed;bottom:25px;right:25px;display:none;width:40px;height:40px;border-radius:50%;background-color:#2E8B57;color:white;text-align:center;line-height:40px;font-size:20px;z-index:100;transition:opacity 0.3s,visibility 0.3s;box-shadow:0 2px 5px rgba(0,0,0,0.3);opacity:0;visibility:hidden}.back-to-top:hover{background-color:#236B43;color:white}.back-to-top.show{display:block;opacity:1;visibility:visible}