@import url('https://fonts.googleapis.com/css2?family=Montserrat:wght@200&display=swap');

body, html {
    margin: 0;
    padding: 0;
    width: 100%;
    height: 100%;
    background-color: #fff;
    display: flex;
    justify-content: center;
    align-items: center;
    overflow: hidden;
    font-family: 'Montserrat', sans-serif;
}

.scene {
    width: 300px;
    height: 300px;
    /* Orthographic projection: NO perspective! This breaks depth perception and creates the Necker illusion */
    perspective: none; 
}

.cube {
    width: 100%;
    height: 100%;
    position: relative;
    transform-style: preserve-3d;
    animation: spin 8s infinite linear;
}

/* Because there is no perspective, objects in the back render exactly the same size as the front */
@keyframes spin {
    0% { transform: rotateX(45deg) rotateY(0deg) rotateZ(0deg); }
    100% { transform: rotateX(45deg) rotateY(360deg) rotateZ(0deg); }
}

.face {
    position: absolute;
    width: 300px;
    height: 300px;
    border: 4px solid #000;
    box-sizing: border-box;
    /* Transparent faces so we only see the wireframe */
    background: transparent;
    /* Ensure lines drawn "behind" others don't have size difference */
}

/* 300px cube means translateZ by half = 150px */
.front  { transform: translateZ(150px); }
.back   { transform: rotateY(180deg) translateZ(150px); }
.left   { transform: rotateY(-90deg) translateZ(150px); }
.right  { transform: rotateY(90deg) translateZ(150px); }
.top    { transform: rotateX(90deg) translateZ(150px); }
.bottom { transform: rotateX(-90deg) translateZ(150px); }

.hint {
    position: absolute;
    bottom: 50px;
    font-size: 1.5rem;
    letter-spacing: 5px;
    color: #555;
    text-align: center;
}