*, *:before, *:after {
    box-sizing: border-box;
    outline: none;
  }
  
  html {
    font-family: "Source Sans Pro", sans-serif;
    font-size: 16px;
    font-smooth: auto;
    font-weight: 300;
    line-height: 1.5;
    color: #444;
  }
  
  body {
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 100%;
    height: 100vh;
    background: linear-gradient(45deg, #dbdedf, #c2eeff);
    overflow: hidden;
  }
  
  code, .card .line-numbers, .card2 .line-numbers {
    font-family: "Lucida Console", Monaco, monospace;
    font-size: 14px;
  }
  
  .card2, .card {
    position: relative;
    width: 30rem;
    height: 15rem;
    perspective: 150rem;
  }
  .card-front, .card-back {
    position: absolute;
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: auto;
    border-radius: 5px;
    box-shadow: 0 1.5rem 4rem rgba(0, 0, 0, 0.4);
    transition: 0.9s cubic-bezier(0.25, 0.8, 0.25, 1);
    backface-visibility: hidden;
    overflow: hidden;
  }
  .card-front:before, .card-front:after, .card-back:before, .card-back:after {
    position: absolute;
  }
  .card-front:before, .card-back:before {
    top: -40px;
    right: -40px;
    content: "";
    width: 80px;
    height: 80px;
    background-color: rgba(255, 255, 255, 0.08);
    transform: rotate(45deg);
    z-index: 1;
  }
  .card-front:after, .card-back:after {
    content: "+";
    top: 0;
    right: 10px;
    font-size: 24px;
    transform: rotate(45deg);
    z-index: 2;
  }
  .card-front {
    width: 100%;
    height: 100%;
    background: linear-gradient(45deg, #101010, #2c3e50);
  }
  .card-front:after {
    color: #212f3c;
  }
  .card-back {
    background: linear-gradient(-45deg, #101010, #2c3e50);
    transform: rotateX(180deg);
  }
  .card-back:after {
    color: #11181f;
  }
  .card:hover .card-front {
    transform: rotateX(-180deg);
  }
  .card:hover .card-back {
    transform: rotateX(0deg);
  }
  .card2 .line-numbers, .card .line-numbers {
    position: absolute;
    top: 0;
    left: 0;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100%;
    margin: 0;
    padding: 0 10px;
    background-color: rgba(255, 255, 255, 0.03);
    font-size: 13px;
  }
  .card2 .line-numbers > div, .card .line-numbers > div {
    padding: 2.5px 0;
    opacity: 0.15;
  }
  .card2 code, .card2 .line-numbers, .card code, .card .line-numbers {
    color: whitesmoke;
  }
  .card2 .indent, .card .indent {
    padding-left: 30px;
  }
  .card2 .operator, .card .operator {
    color: #4dd0e1;
  }
  .card2 .string, .card .string {
    color: #9ccc65;
  }
  a {
    color: #9ccc65;
  }
  .card2 .variable, .card .variable {
    color: #BA68C8;
  }
  .card2 .property, .card .property {
    color: #ef5350;
  }
  .card2 .method, .card .method {
    color: #29b6f6;
  }
  .card2 .function, .card .function {
    color: #FDD835;
  }
  .card2 .boolean, .card .boolean {
    color: #4dd0e1;
  }