body {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background-color: #fc1e8a;
     user-select: none; 
}

.container {
    position: relative;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    gap: 30px;
    background: linear-gradient(325deg, #03001e 0%, #7303c0 30%, #ecbc 70%, #fdeff9 100%);
    padding: 40px 60px;
}

h2 {
    font-size: 3em;
    color: #fff;
    text-transform: uppercase;
    letter-spacing: 0.1em;
}

button {
    padding: 15px 20px;
    width: 100%;
    color: #000;
    background-color: #fff;
    border: none;
    font-size: 1.5em;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    cursor: pointer;
    font-weight: 600;
}

.reset:focus {
    color: #ec38bc;
    background-color: #262809;
}

.game {
  width: 430px;
  height: 430px;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  transform-style: preserve-3d;
  perspective: 500px;
}


.item {
    position: relative;
    width: 100px;
    height: 100px;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: #fff;
  
    font-size: 3em;
    transform: rotateY(180deg);
    transition: 0.25s;
  }

  .item::after {
    content: "";
    position: absolute;
    inset: 0;
    background: #404040;
    /* opacity: 0.85; */
    transition: 0.25s;
    transform: rotateY(0deg);
    backface-visibility: hidden;
  }

.item.boxOpen{
    transform: rotateY(0deg);    
}

.boxOpen::after,
.boxMath::after {
    transform: rotateY(180deg);
}