html, body{
    position: relative;
    margin: 0;
    height: 100%;
    width: 100%;
}

body{
    background-image: url("snow3.gif");
    background-repeat: no-repeat;
    background-size: cover;
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    font-family: 'Work Sans', sans-serif
}
h1, h2, h3, h4 {
    margin: 0.36em;
}
div {
    position: relative;
}

.container {
    margin-top: 4em;
}

.textDiv {
    font-size: xx-large;
    color: white;
    text-align: center;
    margin-top: 2em;
    
}

section * {
    padding: 0;
    margin: 0;
    box-sizing: border-box;
  }

  .memory-game {
    width: 640px;
    height: 640px;
    margin: auto;
    display: flex;
    flex-wrap: wrap;
    perspective: 1000px;
  }
  
  .memory-card {
    width: calc(25% - 10px);
    height: calc(33.333% - 10px);
    margin: 5px;
    position: relative;
    transform: scale(1);
    transform-style: preserve-3d;
    transition: transform .5s;
    box-shadow: 1px 1px 1px rgba(0,0,0,.3);
  }
  
  .memory-card:active {
    transform: scale(0.97);
    transition: transform .2s;
  }
  
  .memory-card.flip {
    transform: rotateY(180deg);
  }
  
  .front-face,
  .back-face {
    width: 100%;
    height: 100%;
    padding: 20px;
    position: absolute;
    border-radius: 5px;
    background: rgba(177, 216, 251, 0.5);
    backface-visibility: hidden;
    -webkit-backface-visibility: hidden;
  }
  
  .front-face {
    transform: rotateY(180deg);
  }

  .yes {
    position: absolute;
    font-size: 128px;
    color: #fff;
    margin: auto;
    width: 100%;
    text-align: center;
    opacity: 0;
  }

  .fade-out {
      opacity: 0;
      transition: opacity 1000ms;
  }

  .fade-in {
    opacity: 1;
    transition: opacity 1500ms linear 800ms;
  } 

  .cover.fade-inish {
    opacity: 0.7;
    transition: opacity 1000ms;
  }

.cover {
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    background: rgb(42 46 76);
    opacity: 0.4;
}