#scrollToTopBtn {
    position: fixed;
    bottom: 3vw;
    right: 3vw;
    z-index: 999;
    background: transparent;
    border: none;
    outline: none;
    cursor: pointer;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.33s cubic-bezier(.45,2,.4,1), box-shadow 0.3s;
    width: 5vw;
    height: 5vw;
    min-width: 62px;
    min-height: 62px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: none;
}
#scrollToTopBtn.show {
    opacity: 1;
    pointer-events: all;
}
.scroll-btn-glow {
    position: absolute;
    left: 50%; top: 50%;
    transform: translate(-50%, -50%);
    width: 5vw; height: 5vw;
    min-width: 62px; min-height: 62px;
    border-radius: 50%;
    background: radial-gradient(circle at 60% 40%, #4bf1f740 0%, transparent 80%);
    z-index: 1;
    filter: blur(0.12vw);
    pointer-events: none;
    animation: btnGlow 3s infinite alternate;
    transition: background 0.2s;
}
@keyframes btnGlow {
    from { opacity: 0.55;}
    to   { opacity: 0.33;}
}
.scroll-btn-svg {
    width: 3.7vw; height: 3.7vw;
    min-width: 46px; min-height: 46px;
    z-index: 2;
    display: block;
}
#scrollToTopBtn svg circle {
    stroke: #4bf1f7;
    stroke-width: 0.5;
    filter: drop-shadow(0 0 0.13vw #24d1e53a);
}
#scrollToTopBtn:hover .scroll-btn-glow {
    background: radial-gradient(circle at 50% 55%, #4bf1f770 0%, #fff68511 80%, transparent 100%);
}
#scrollToTopBtn:hover .scroll-btn-svg polyline {
    stroke: #fff685;
    filter: drop-shadow(0 0 0.3vw #4bf1f7b3);
}
#scrollToTopBtn:active .scroll-btn-glow {
    opacity: 0.77;
}

/* Tablet */
@media (orientation:portrait) {
    #scrollToTopBtn {
        width: 18vw;
        height: 18vw;
        min-width: 62px;
        min-height: 62px;
        right: 3vw;
        bottom: 24vw;
    }
    .scroll-btn-glow {
        width: 18vw;
        height: 18vw;
        min-width: 62px;
        min-height: 62px;
    }
    .scroll-btn-svg {
        width: 12vw;
        height: 12vw;
        min-width: 46px;
        min-height: 46px;
    }
}