@import url('https://fonts.googleapis.com/css2?family=Berkshire+Swash&display=swap');

*, *::before, *::after {
    padding: 0;
    margin: 0 auto;
    box-sizing: border-box;
}

:root {
    --boxSize: 1em;
    --speed: 18s;
    --rotateSceneX: -0deg; 
    --rotateSceneY: 0deg; 
}

$signColor: #544;

body {
    font-family: 'Berkshire Swash', cursive;
    background-color: #aaa;
    height: 100vh;
    display: grid;
    grid-template-columns: repeat(10, 1fr);
    grid-template-rows: repeat(10, 1fr);
    perspective: 100em;
    overflow: hidden;
}

.cell {
    width: 100%; height: 100%;

    @for $i from 0 to 10 {
        &:nth-child(10n + #{$i + 1}):hover ~ .scene {
            --rotateSceneY: #{-63 + ($i * 14)}deg;
        }
        &:nth-child(n + #{10 * $i + 1}):nth-child(-n + #{10 * ($i + 1)}):hover ~ .scene {
            --rotateSceneX: #{36 - ($i * 8)}deg;
        }
    }
}

.scene {
    position: fixed;
    top: 50%; left: 50%;
    transform-style: preserve-3d;
    transform: translateZ(-0em) rotateX(var(--rotateSceneX)) rotateY(var(--rotateSceneY));
    transition: transform 0.5s;
    z-index: -1;
}

.sign {
    position: absolute;
    top: -14.25em; left: -26em;
    width: 52em; height: 28.5em;
    background-color: darken($signColor, 30%);
    transform-style: preserve-3d;

    &_front {
        width: 100%; height: 100%;
        transform: translateZ(2em);
        background-image:
            linear-gradient(0deg,   $signColor 2em, transparent 2em),
            linear-gradient(90deg,  $signColor 2em, transparent 2em),
            linear-gradient(180deg, $signColor 2em, transparent 2em),
            linear-gradient(270deg, $signColor 2em, transparent 2em)
        ;
    }

    &_topIn, &_topOut {
        position: absolute;
        height: 2em;
        background-color: lighten($signColor, 5%);
        transform-origin: top;
        transform: rotateX(90deg);
    }
    &_topIn {
        bottom: 0; left: 2em;
        width: calc(100% - 4em);
    }
    &_topOut {
        top: 0; left: 0;
        width: 100%;
    }
    
    &_bottomIn, &_bottomOut {
        position: absolute;
        height: 2em;
        background-color: darken($signColor, 15%);
        transform-origin: bottom;
        transform: rotateX(-90deg);
    }
    &_bottomIn {
        top: 0; left: 2em;
        width: calc(100% - 4em);
    }
    &_bottomOut {
        bottom: 0; left: 0;
        width: 100%;
    }
    
    &_leftIn, &_leftOut {
        position: absolute;
        width: 2em;
        background-color: darken($signColor, 5%);
        transform-origin: left;
        transform: rotateY(-90deg);
    }
    &_leftIn {
        top: 2em; right: 0;
        height: calc(100% - 4em);
    }
    &_leftOut {
        top: 0; left: 0;
        height: 100%;
    }

    &_rightIn, &_rightOut {
        position: absolute;
        width: 2em;
        background-color: darken($signColor, 10%);
        transform-origin: right;
        transform: rotateY(90deg);
    }
    &_rightIn {
        top: 2em; left: 0;
        height: calc(100% - 4em);
    }
    &_rightOut {
        top: 0; right: 0;
        height: 100%;
    }

    &_segment {
        position: absolute;
        top: 2em;
        width: 2em; height: 24.5em; 
        transform: translateX(-50%) translateZ(1em);
        transform-style: preserve-3d;

        @for $p from 0 to 24 {
            &:nth-child(#{$p + 1}) {
                left: #{3 + ($p * 2)}em;
                --ad: #{$p};
            }
        }

        &::before {
            content: '';
            position: absolute;
            top: 0; left: 0.5em;
            width: 1em; height: 100%;
            background-image: linear-gradient(90deg,  #333, #aaa, #333);
            transform: rotateY(calc(var(--rotateSceneY) * -1));
        }

        & > div {
            position: absolute;
            top: 0.25em; left: 0.05em;
            width: 1.9em; height: 24em;
            animation: signflip var(--speed) cubic-bezier(.5,0,.7,1.5) infinite;
            overflow: hidden;
            background-position: calc(var(--ad) / 23 * 100%) 50%;
            background-size: 48em 24em;
            text-align: center;

            @for $i from 0 to 3 {
                &:nth-child(#{$i + 1}) {
                    background-image: url('https://assets.codepen.io/1948355/trivision#{$i + 1}.jpg');
                    animation-delay: calc((var(--speed) * #{$i / -3}) - var(--speed) + (var(--ad) * 0.1s));
                    box-shadow: 0 0 1em #0007 inset;

                    &::after {
                        background-image: inherit;
                    }
                }
            }
            
            $d: 0.53em;
            @keyframes signflip {
                0%, 26.666% { transform: rotateY(0deg) translateZ(#{$d}); }
                33.333%, 60% { transform: rotateY(120deg) translateZ(#{$d}); }
                66.666%, 93.333% { transform: rotateY(240deg) translateZ(#{$d}); }
                100% { transform: rotateY(360deg) translateZ(#{$d}); }
            }

            &:nth-child(1)::after {
                content: "DREAM";
                position: absolute;
                top: 0; left: calc(var(--ad) * -0.2em);
                font-size: 10em;
                width: 4.8em; height: 2.4em;
                padding-top: 0.6em;
                background-size: 4.8em 2.4em;
                filter: drop-shadow(0 0 0.1em #fff) drop-shadow(0 0 0.5em #00f);
                background-clip: text;
                -webkit-background-clip: text;
                color: transparent;
            }

            &:nth-child(2)::after {
                content: "LOVE";
                position: absolute;
                top: 0.8em; left: calc(var(--ad) * -0.2em);
                font-size: 10em;
                width: 3.4em;
                filter: drop-shadow(0 0 0.1em #000);
                background-size: 5.2em 2.6em;
                background-position: right top;
                background-clip: text;
                -webkit-background-clip: text;
                color: transparent;
            }

            &:nth-child(3)::after {
                content: "HOPE";
                position: absolute;
                top: 0; left: calc(var(--ad) * -0.25em);
                font-size: 8em;
                width: 6em; height: 3em;
                padding: 1.5em 0 0 2.1em;
                background-image: url('https://assets.codepen.io/1948355/trivision4.jpg');
                background-size: 100%;
                filter: drop-shadow(-0.025em 0.025em 0.05em #fff);
                background-clip: text;
                -webkit-background-clip: text;
                color: transparent;
            }
        }
    }
}

.shadow {
    position: fixed;
    top: 50%; left: 50%;
    width: 65em; height: 36em;
    transform: translate(-50%, -50%) translateZ(-20em);
    background-color: #0003;
    filter: blur(3em);
}