body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

h2 {
  margin: .25rem;
}

div.container {
  margin: auto;
  display: flex;
  flex-direction: column;
  align-items: center;
}

button {
  padding: 1rem;
  background-color: skyblue;
}

#coin {
  position: relative;
  width: 15rem;
  height: 15rem;
  margin: 2rem 0rem;
  transform-style: preserve-3d;

}

#coin div {
  width: 100%;
  height: 100%;
  /* border: 2px solid black; */
  border-radius: 50%;
  backface-visibility: hidden;
  background-size: contain;
  position: absolute;
}

.heads {
    background-image: url("https://images2.imgbox.com/aa/96/X5kr2ikj_o.png");
}

.animate-heads {
  animation: flipHeads 3s;
  animation-fill-mode: forwards;
}

@keyframes flipHeads {
  from {
    transform: rotateY(0deg);
  }
  to {
    transform: rotateY(1800deg);
  }
}

.tails {
    background-image: url("https://images2.imgbox.com/93/24/4unjGDhZ_o.png");
  transform: rotateY(-180deg);
}

.animate-tails {
  animation: flipTails 3s;
  animation-fill-mode: forwards;
}

@keyframes flipTails {
  from {
    transform: rotateY(0deg);
  }
  to {
    transform: rotateY(1620deg);
  }
}

.article {
  padding: 2% 10%;
}