/* Background Effects — overlays lourds uniquement en high-perf */
.noise-overlay,
.scanlines {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
}

.high-perf .noise-overlay {
    display: block;
    z-index: 9999;
    opacity: 0.03;
    background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 200 200' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noise'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%' height='100%' filter='url(%23noise)'/%3E%3C/svg%3E");
}

.high-perf .scanlines {
    display: block;
    z-index: 9998;
    background: repeating-linear-gradient(
        0deg,
        rgba(0, 0, 0, 0.15) 0px,
        rgba(0, 0, 0, 0.15) 1px,
        transparent 1px,
        transparent 2px
    );
    opacity: 0.45;
}

#particles {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 1;
}

.grid-bg {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 0;
    background-image: 
        linear-gradient(rgba(0, 240, 255, 0.02) 1px, transparent 1px),
        linear-gradient(90deg, rgba(0, 240, 255, 0.02) 1px, transparent 1px);
    background-size: 80px 80px;
}

.high-perf .grid-bg {
    mask-image: radial-gradient(ellipse at center, black 0%, transparent 70%);
    -webkit-mask-image: radial-gradient(ellipse at center, black 0%, transparent 70%);
}

.medium-perf .grid-bg {
    opacity: 0.5;
}

.low-perf .grid-bg {
    display: none;
}