.grid-back {
    position: fixed;
    inset: 0;
    background:
      linear-gradient(rgba(0, 255, 255, 0.1), transparent 1px),
      linear-gradient(90deg, rgba(0, 255, 255, 0.1), transparent 1px);
    background-size: 100px 100px;
    filter: drop-shadow(0 0 8px rgba(0, 255, 255, 0.7))
            drop-shadow(0 0 16px rgba(0, 255, 255, 0.9));
            z-index: 0;
    animation: drift 100s linear infinite;
}

.grid-back::before{
    content: "";
    position: absolute;
    inset: 0;
    pointer-events: none;
    background: radial-gradient(circle at top left, rgba(0, 255, 255, 0.12), transparent);
}
@keyframes drift {
    0%{background-position: 0 0;}
    100%{background-position: 100px 100px;}
}