*, *: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, #E91E63, #9C27B0);
      overflow: hidden;
}

code, .card .line-numbers {
  font-family: "Lucida Console", Monaco, monospace;
  font-size: 14px;
}

.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);
}
.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;
}
.card .line-numbers > div {
  padding: 2.5px 0;
  opacity: 0.15;
}
.card code, .card .line-numbers {
  color: whitesmoke;
}
.card .indent {
  padding-left: 30px;
}
.card .operator {
  color: #4dd0e1;
}
.card .string {
  color: #9ccc65;
}
.card .variable {
  color: #BA68C8;
}
.card .property {
  color: #ef5350;
}
.card .method {
  color: #29b6f6;
}
.card .function {
  color: #FDD835;
}
.card .boolean {
  color: #4dd0e1;
}