.back-to-top{position:fixed;bottom:30px;right:30px;width:50px;height:50px;background-color:var(--primary-color);color:#fff;border:none;cursor:pointer;display:flex;align-items:center;justify-content:center;opacity:0;visibility:hidden;transition:all 0.3s ease;z-index:999;box-shadow:var(--shadow-md)}.back-to-top.show{opacity:1;visibility:visible}.back-to-top:hover{background-color:var(--secondary-color);transform:translateY(-5px);box-shadow:var(--shadow-lg)}.back-to-top svg{width:24px;height:24px;stroke:currentColor}@media (max-width:768px){.back-to-top{bottom:20px;right:20px;width:45px;height:45px}.back-to-top svg{width:20px;height:20px}}