.cube {
    position: relative;
    transform-style: preserve-3d;
    transform: perspective(1500px); 
    transform: rotateX(-20deg) rotateY(-25deg);
    transition: transform 0.5s;
    top: 10px;
    left: 10px;
    z-index: 0;
}

.block {
    border: 3px solid lightgray;
    flex: 0 0 30px;
    margin: 0;
    outline-width: 0;
}

.rotated {
    transform: rotateX(-20deg) rotateY(155deg);
}

.rotated > .face {
    opacity: 0.8;
}

.face {
    width: 90px;
    height: 90px;
    position: absolute;
    background: rgba(170, 170, 170, 1.0);
    /*border: 1px solid #ccc;*/
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 24px;
    font-weight: bold;
    flex-wrap: wrap;
    z-index: 0;
}

.front { 
    transform: translateZ(45px); 
}
.back { 
    transform: rotateY(180deg) translateZ(45px);
}
.left { 
    transform: rotateY(-90deg) translateZ(45px);
}
.right { 
    transform: rotateY(90deg) translateZ(45px); 
}
.up { 
    transform: rotateX(90deg) translateZ(45px); 
}
.down { 
    transform: rotateX(-90deg) translateZ(45px); 
}

.fb {
    background-color: blue;
}
.bb {
    background-color: green;
}
.rb {
    background-color: red;
}
.lb {
    background-color: orange;
}
.ub {
    background-color: yellow;
}
.db {
    background-color: white;
}

.mask .mask-box .mask-box {
    margin: 20px 0;
    color: white;
}