:root {
    --bg: #070a0e;
    --teal: #00e5ff;
    --grid: rgba(0, 229, 255, .10);
    --glowSoft: rgba(0, 229, 255, .12);
}

#bg-tech-clean.theme {
    background: var(--bg);
}

/* 確保所有子元素不吃事件 */
#bg-tech-clean,
#bg-tech-clean .floor,
#bg-tech-clean .scan,
#bg-tech-clean #dots {
    pointer-events: none;
}

/* 3D 透視地平線（雙向格線，恢復流動） */
#bg-tech-clean .floor {
    position: fixed;
    inset: 0;
    z-index: 0;
    top: 30%;
    transform: perspective(800px) rotateX(65deg);
    transform-origin: 50% 0;
    background-image:
        linear-gradient(var(--grid) 1px, transparent 1px),
        linear-gradient(90deg, var(--grid) 1px, transparent 1px);
    background-size: 60px 60px;
    animation: gridSlide 14s linear infinite;
    box-shadow: 0 -120px 160px -120px var(--glowSoft) inset;
}

@keyframes gridSlide {
    from {
        background-position: 0 0, 0 0;
    }

    to {
        background-position: 0 60px, 60px 0;
    }
}

/* 掃描線 */
#bg-tech-clean .scan {
    position: fixed;
    inset: 0;
    z-index: 0;
    background: linear-gradient(to bottom, transparent 40%, rgba(0, 229, 255, .10) 50%, transparent 60%);
    background-size: 100% 200%;
    mix-blend-mode: screen;
    animation: scanMove 6s linear infinite;
}

@keyframes scanMove {
    from {
        background-position: 0 -100%;
    }

    to {
        background-position: 0 100%;
    }
}

/* RWD：縮小格線密度並微調視角高度與掃描速度 */
@media (max-width: 1024px) {
    #bg-tech-clean .floor {
        background-size: 52px 52px;
        top: 32%;
    }

    #bg-tech-clean .scan {
        animation-duration: 7s;
    }
}

@media (max-width: 768px) {
    #bg-tech-clean .floor {
        background-size: 44px 44px;
        top: 36%;
    }

    #bg-tech-clean .scan {
        animation-duration: 8s;
    }
}

@media (max-width: 480px) {
    #bg-tech-clean .floor {
        background-size: 36px 36px;
        top: 40%;
    }

    #bg-tech-clean .scan {
        animation-duration: 9s;
    }
}