/* Scroll to Top Button */
.scroll-top-btn {
    position: fixed;
    bottom: 24px;
    right: 24px;
    width: 48px;
    height: 48px;
    background: var(--gradient-primary);
    color: white;
    border: none;
    border-radius: var(--radius-xl);
    font-size: 1.1rem;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transform: translateY(100px) scale(0.8);
    transition: all var(--transition-slow);
    z-index: 1000;
    box-shadow: var(--shadow-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    touch-action: manipulation;
    animation: glow 2s ease-in-out infinite;
    backdrop-filter: blur(10px);
}

@keyframes glow {
    0%, 100% {
        box-shadow: var(--shadow-lg);
        transform: scale(1);
    }
    50% {
        box-shadow: var(--shadow-xl);
        transform: scale(1.05);
    }
}

.scroll-top-btn.visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0) scale(1);
}

.scroll-top-btn:hover {
    background: var(--gradient-secondary);
    transform: translateY(-4px) scale(1.1);
    box-shadow: var(--shadow-hover);
    animation: none;
}

.scroll-top-btn:active {
    transform: translateY(-2px) scale(1.05);
}