/* quick reset and base styles */
* {
    margin: 0;
    padding: 0;
    border: 0;
  }
  
  html {
    font-family: helvetica, arial, sans-serif;
  }
  
  /* relevant styles */
  .img__wrap {
    position: relative;
    height: 90%;
    width: 60%;
  }
  
  .img__description_layer {
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    background: rgba(72, 71, 78, 0.6);
    color: #fff;
    visibility: hidden;
    opacity: 0;
    display: flex;
    align-items: center;
    justify-content: center;
  
    /* transition effect. not necessary */
    transition: opacity .2s, visibility .2s;
  }
  
  .img__wrap:hover .img__description_layer {
    visibility: visible;
    opacity: 1;
  }
  
  .img__description {
    transition: .2s;
    transform: translateY(1em);
  }
  
  .img__wrap:hover .img__description {
    transform: translateY(0);
  }