.bg-fixed {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: url('https://images.unsplash.com/photo-1516589174184-c685265162fb?auto=format&fit=crop&w=1200&q=80') no-repeat center center;
    background-size: cover;
    z-index: -2;
}

.bg-mask {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(255, 255, 255, 0.15);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    z-index: -1;
}